Gear: Tender


Our Tender Requirements

Inmar

When it comes to a Tender or Dinghy, everyone is looking for something specifically tailored to their individual needs... and we are no different.  Here are our top 10 requirements when looking at a tender or dinghy, the 'car' for your boat.

  1. Low Weight - On a cat, weight always matters. Due to this, we won't be going with a hydraulic platform (as much as we would like to) because most of them cannot lift our dinghy choices!  Plus, if we choose a light enough dinghy, we can drag it on shore.  190 pounds or less is our goal.
  2. Open Space - With S/V Lynx carrying a larger crew than a typical boat, we need a tender that can handle our crew.
  3. Durability - The hull has to withstand beaching and the tube material must resist UV light, so we prefer Hypalon.
  4. Hull Shape - Deep V.  If we want a smoother ride in rough waves we need a higher dead rise with a deep V hull.
  5. Tube Diameter - The larger the diameter, the better for a drier ride.  We don't like getting wet, either from our butts hanging over the edge of a pontoon and getting splashed or due to spray from wave impacts dousing our entire bodies on our way to shore for a nice dinner.  We are looking for 18" tubes.
  6. Length - This matters because we have to fit this between our cat hulls, and 13' 9" is about the maximum width without encroaching on the sugar scoops. Therefore, we need a dinghy length of 13' or less.  Ideally, the length would be about 12'.
  7. Load capacity - We are scuba divers, so we need a boat that will handle all our gear and multiple divers and still get on a plain, 1500 pounds of LCC is our target.
  8. Double Floor- We like our feet and items to stay dry, so a double floor keeps more water in the boat away from where your feet are standing.
  9. Double Storage Lockers in the bow: This is so that we can put one of our batteries in the large compartment, and our anchor and chain in the other smaller one.
  10. Price - Money is not unlimited, so this is a serious factor we have to consider.  Our budget is about $6,000

Hull Types

When it comes to hulls on a Tender or Dinghy, there are three options, Carbon Fiber, Fiberglass or Aluminum.  Here are our thoughts on which is the best hull material for our needs.  We have five areas of comparison:

  • WEIGHT - First off, many claim that aluminum RIBs are lighter than fiberglass... and we have found this to be generally true.  However, carbon fiber is even lighter.  Therefore, all the RIBS on our list of contenders have aluminum or carbon fiber hulls.
  • DURABILITY - Next up is durability. If you plan on running your tender up onto shores covered with rocks, then the aluminum hull is your best bet as it is more scratch resistant and will tend to dent rather than fracture.  However, there have been issues of aluminum hull welds cracking over time with the flexing of the boat, where fiberglass is more forgiving in this area and carbon fiber even far stronger   Also, even though aluminum hulls are tougher against scratches, if you do get a scratch in your fiberglass or carbon fiber boat, you can easily mix up some epoxy and do a repair.   Fixing any serious issue with an aluminum hull is far more difficult. 
  • CORROSION - This is more likely on an aluminum hull.  You can have one powder coated or painted, but then you risk bubbling of the paint.  Some owners have reported this issue while others have no problems at all.  Many people suggest a bare aluminum hull as the best bet.   However, as one RIB maker states on their website, "Aluminum requires very little maintenance other than keeping salt off to protect the hull from corrosion."  I guess the issue here is that we are going to be in salt water... constantly.    Fiberglass and carbon fiber would have less issues with corrosion.
  • SHAPE - Fiberglass and carbon fiber boats can have a more polished and contoured hulls since they can be made in any shape where Aluminum has some limitations and tend to stick to a somewhat flat sided shape, with small ridges (see pics, below - fiberglass left, aluminum right).
  • NOISE -Aluminum hulls are nosier, where fiberglass or carbon fiber are easier on the ears. 
Fiberglass

Fiberglass or Carbon

Alum Hull

Aluminum

Our Conclusion on Hull Material

Though fiberglass hulls seem to have a lot going for them, in the end, we prefer the better durability of the aluminum hulls for beaching.  Carbon fiber is a lot stronger than fiberglass, and more scratch resistant, so we did not rule out that option.  Therefore, in the comparisons (below) all of the contenders have aluminum or carbon fiber hulls.


Comparisons of Models

Inmar, Model 365R-AL

Next is the 12' inflatable from Inmar. She is a light weight boat at 185 pounds Hypalon even though she has twin decks and a deep V hull.  This boat is listed as 6 passengers, which is less than we would like, but has a 1525 pound load carrying capacity, so we could squeeze in a couple more!  Like our three top contenders, the 365R-AL has 18" tubes, so that's a big plus.   The max hp for the outboard is 30 hp, so that works for our electric 24 hp outboard (18 kw). 

In features, the 365R-AL compares well against the ZAR Mini and North Atlantic and comes in at a good price of only $5,595, plus tax and transport equals $6364.86 total.  Because the dealer is fairly local, there are no delivery costs to us.  That makes the 365R-AL the best priced boat we are considering if you take shipping and tax into account. 

Standard Features: 
Non-skid aluminum hull with deep "V", bow locker (fuel tank space with straps), double wall floor, aluminum outboard mounting plate, self bailer, leafield valves, over inflation valve, molded handles, heavy duty full length rubstrake, (3) davit lifting points, bow tow rings, oar locks with oars, removable rowing seat, foot pump with gauge, repair kit. 

Her only real negatives are that she is only 12' long, losing six inches to the Zar and N. Atlantic, and Inmar isn't a world wide boat distributor, like Highfield or ZAR, hence, the lower price.  Still, there are advantages to the 12' length, as it will be an easier fit between our sugar scoops.  

UPDATE: We have decided!  We ordered our 365R-AL!

Inmar

Zar Mini Rib, Model 13 HDL

The ZAR Mini is a twin deck aluminum hull boat with a double bow locker. She is 12'6" long, has a tube diameter of 18" and weights in at 201 lbs. She is rated for seven passengers, and has a payload of 1521 lbs. These are all excellent numbers for S/V Lynx!

Her main RIB competitors will be the North Atlantic and Inmar 365R-AL.  It isn't the lightest boat on our list, in fact, the ZAR loses in weight to the Cadet by 38 pounds and the OC400 by 54 pounds.  And compared to the other top contender, the Mini is about 16 pounds heavier than the Inmar boat.

Her length is six inches longer than the Inmar, giving her a bit more interior space and she is 5" wider, at 6'5".  The width is desirable but the added length makes her harder to fit between our sugar scoops.   Finally, by price, she costs $10,700 (with shipping and tax include).  That is significantly more than the final price of the Inmar.

It was a close call between the Zar Mini 13, but we went with the Inmar 365R-AL due to a far better price and a little weight savings.

Zar Mini

North Atlantic, Model ALA380L

Next is the 12' 8" inflatable from North Atlantic. She is a light weight boat at 175 pounds in PVC even though she has twin decks and a deep V hull.   That weight will to up round 20 pounds once we switch to Hypalon material for the tubes.  This boat is listed as a 6 passenger boat, but has a 1550 pound load carrying capacity, even better than the Zar and around the same as the Inmar. 

Like those boats, the ALA380L has 18" tubes, so that's a big plus. The max hp for the outboard is 30 hp, so that works for our electric 24 hp outboard (18 kw).  The ALA380L is likely about the same weight as the Mini in Hypalon, but loses to the Inmar.

In features, the ALA380L compares well against the ZAR Mini and Inmar 365R-AL with the exceptions of only having a single locker up front instead of dual lockers like the other two top contenders and being 12'8" which is a bit long for our desires.   

Also, like the Inmar, the North Atlantic isn't a major boat name like Highfield or ZAR, who both have worldwide distributors.  Finally, the boat must be shipped from Maine to us in California.  That will add another $1400 to the price. 

So, the total price of $6324.  That is about the same price as the Inmar 365R-AL.  However, with the Inmar we get to purchase locally and get our dual front lockers, and our preferred length, so that is the clear choice.

North Atlantic

Highfield, Model CL 380

Like her smaller sister, the CL360 (see next entry), she is still a light boat at 183 lbs, but 8" longer than the CL360. The beam is 2" wider than her sister boat, coming in at 5'8" and the weight capacity is more at 1404 lbs. The hull is the same with a dead rise of 15 degrees with a moderate V hull. And, the maximum size motor is also 30 hp.

So, what makes either Highfield Classics so desirable? Well, like the ZAR, NA, and Inmar, it all has to do with the weight.  If we go with one of these much lighter boats, it opens up the possibility to use an electric vs a gas outboard. That means, we don't have to store flammable gas on board the main catamaran and we can refill our fuel (batteries) off our solar panels. (More on this, in Electric Propulsion, below) and share them with the main catamaran when needed.

The price is a bit higher than the three top contenders since the CL 380 runs $7,214, without shipping and tax included, so it will likely be quite a bit more.

Still, this boat was one of the top contenders, in fourth place.

Highfield CL380

Highfield, CL 360

By going down to a bit in length, we can save a little weight and money over the CL 380.  Besides shedding 18 pounds over the CL 380, the price also drops by about $600.  At 165 pounds, she is only 18 pounds heavier than the lightest boat on our list, the OC400.  As for ribs, the Cadet is 2 pounds lighter, but she comes only has 16" tubes, while the CL360 has 17" tubes.  She is the same width, 5'6" as the Cadet. The problem with this smaller boat is that she is only rated for six passengers, with smaller a payload of 1237 lbs.

The main advantages are her weight and shorter length for an easier fit between the sugar scoops.
This is a decent boat, just a bit light on the load carrying capacity for us.

Highfield CL360

Zodiac, Model Cadet 390 DL RIB NEO

The Zodiac Cadet is the lightest twin deck aluminum RIB we have found, coming in at 163 pounds, that's 2 pounds lighter than the closest competitor we have found, the CL 360 but 16 pounds heavier than the OC400.

This boat is rated for seven passengers.   If the Cadet has a downside, it is the 16" tubes, where the CL 360 or 380 have 17" tubes and the ZAR, NA, and Inmar have 18" tubes.  The Cadet also has a smaller payload and will be a little less stable and wetter ride.  The max payload is 1418, a little less than the CL380 by 103 lbs. Her length is also slightly worse for fitting between the sugar scoops, though the CL380 is only five inches shorter.  Anything under 13' would work.

Like the N.A., Zar, and Inmar RIBs, this boat also includes a double forward storage locker.  Her biggest plus is that her tubes slide off the hull in case they ever need to be replaced (unique to Zodiac boats).

The hull is a medium V, so good for plaining, but not our desired Deep-V.

The lighter weight really make this boat interesting for us, as does her low price.  This would make an excellent electric propulsion boat!  The maximum size outboard is a 30 hp, so the 20 hp Stealth electric outboard would work fine.  The total weight of this boat, with the Stealth electric propulsion is 467 pounds. With the Spirit 1.0 plus (for beaching) this seven person, nearly 13' tender only weighs 207 lbs!  However, those narrow  tubes are a real issue for us so we will likely not go with this boat. 

Zodiac

Offshore Cruising Tenders: OC400
This is an all carbon fiber, hard shell, boat.  She will plane faster, but may have a slightly harder ride in heavy seas.  Unfortunately, she comes with a single floor, so she will be wetter ride unless you sponge out al the water, immediately.  The OC400 has a deeper V than other Offshore Cruising models, so that will help. 

Most importantly, the OC400 is lighter than any of our other contenders, and 54 pounds less than our top choice of RIB!   This carbon fiber hull should last as long as we own the boat and have good resale value.  But a large negative is the initial cost, which is more than twice as much as the Zar Mini or Inmar.  At $14,000, the high price was the main factor where we decided to go with the Inmar RIB.


Overall length (m/ft): 3.91 / 12.82ft
Overall width (m/ft): 1.72 / 5.64ft
Bow top side height (m/ft): 0.79 / 2.59ft
Stern height (m/ft): 0.61/2ft
Overall bow height: 0.60 / 1.11ft
Carbon hull weight is 67kg (147.7 Pounds)
Max recommended hp: 20hp
Short Shaft
Preliminary Max load 602kg (1327.18 pounds)



OC400

Point Comparison Chart

We assigned a point value to each feature based on their importance to us.  This allows us to get a quick comparison of the tenders we are interested in possibly buying.  Don't forget to scroll to the right to see more of the chart, including the final totals. 

Tenders Weight Pts People Pts Hull PtsTubes PtsLength PtsLCC Pts Price PtsLasts Pts Total
Zar Mini 132011675Deep-V718"1212'6"715128$10,600*1010 yrs464
ALA380L1951664Deep-V718"1212'8"515508$6,324*1610 yrs469
HF_CL3801831775Modr._V517"812'6"714047$7,2141410 yrs463
Zodiac Cd.1631975Modr._V516"412'11"414187$5,4921710 yrs461
HF_CL3601651964Modr._V517"411'10"512373$6,5881510 yrs459
Inmar365R1851764Deep_V718"1212'615258$6,365*1610yrs474
OC4001472164Shal._V3Hard1212'10"513275$14,000*730yrs1266
Showing entries (filtered from total entries)
NOTE: Prices with an asterisk (*) already have shipping, tax, and any other fees to California added, all other prices will be higher than indicated once those are added. 

Our Conclusion on Tenders


Our top desires are low weight, double floor, large tubes, and 12' length.  The total price also figures in heavily as well.  So, looking at those factors, the Zar Mini RIB 13 and the Inmar 356R-AL were our top contenders.

They are very similar in features, with the main differences being that the Zar is 6" wider, and 6" longer, while the Inmar is 16 pounds lighter and $4,300 less expensive!  (That was a big one).  

Zar Mini

Therefor, the Inmar 365R-AL came in as our #1 boat, 5 points ahead of the North Atlantic, 8 points ahead of the OC, and 10 points ahead of the Zar.  

We will pare an electric 24 hp motor and 230 ah of 48v LifePO4 batteries built in waterproof cases (see our tender, see it here).  Then, we'll add a Spirit 1.0 Evo as a backup motor (see below).   As for which Electric motors we will use on our tender, that's up next.

Though we like the North Atlantic, OC, and Zar boats, the Inmar won out on a combination of price, weight, and having all our desired features, so that is the boat we ordered.
Sea trials and videos to follow in October, 2022.

Inmar

Dinghy Motors

Stealth

The first choices to make are a gas, electric, or jet.

There are advantages and disadvantages to these three options, as follows:

Advantages

  • Gas outboards - They can have higher horsepower as we are limited by the 48v battery voltage with electric outboards.  They have greater range on a single excursion since gas is more energy dense than batteries.  They also weigh 87 pounds less if you count the engine and gas vs an electric motor and batteries.  Most importantly, they are far less expensive to purchase than electric outboards and their batteries.
  • Electric outboards - They require no gas stored on the tender or main boat and have endless numbers of excursions due to available solar recharging on the main boat.  They make no fumes and are quieter.  They start without a pull cord, and do so, every time.  They require no warm up time before heading out  They can be lighter on the stern of the tender (battery weight can be moved forward).  There is less weight on the main boat since we don't have to store flammable gasoline.  They have high torque at any RPM, helping to get the tender on a plain.  When planning a beach landing in surf, we can swap out the large motor and batteries for a smaller electric, waterproof, outboard.  Our remaining range can be monitored from a cell phone.  We can carry a spare small electric outboard for emergencies.
  • Electric Jet - We only have one option here, and it is a new one.  The two big advantages are no propeller to break and nothing sticks down, making your boat shallower draft, with no need to raise (tilt) an engine.

Disadvantages

  • Gas outboards - They can have trouble starting.  They require far more maintenance, They have flammable fuel, which require trips to find gas to refill.  Gas outboards have a limited number of excursions before running out of fuel.  And, they require extra, flammable, fuel to be stored on your main boat.
  • Electric outboards - With the batteries, they are heavier by 87 pounds.  They are limited in range on a single excursion if you desire to 'go fast' (slowing down extends range significantly).  Price!  If you add the batteries, they are far more expensive than gas outboards by about $4,200.
  • Electric Jet - At 19hp, it has less horsepower than a gas (25hp) or electric (24hp) outboards.  With the batteries, they are heavier than the gas option.  They have limited range on a single excursion if you desire to 'go fast' (slowing down extends range significantly).   Unfortunately, they are far more expensive at $14,743 (jet plus proprietary batteries) vs $8,500 for the electric outboard and our batteries, or just $4,300 for the gas outboard.  Finally, the mounting is permanent, so we cannot remove the jet from the tender if we want to add a Spirit 1.0 Evo for beaching in surf and dragging up the beach.

Our choice between Gas, Electric Outboard, or Electric Jet

We have decided to buy an electric outboard.  Our choice came down to having to deal with all the hassles of starting and warming up a gas engine, procuring fuel, storing a extra flammable fuel on the main boat, smelling nasty fumes, doing less maintenance, and having endless excursions without running out of fuel in remote locations.  Therefore, electric won, hands down.  Because of all these advantages, we are willing to pay the extra money to go electric.  As for the electric jet, it is too expensive while offering less horsepower, but even if we were willing to spend the money, the fact that we cannot remove it easily to change to a smaller outboard ruled it out. 

Note that the prices below are just the motor, we will have to add an additional $3,000 for our 11,000 watt lithium tender batteries.

Below are the electric outboard options we considered:

E18KW

Stealth E18KW

* 18 kW continuous power
* Plane a boat that weighs 1,500 lbs. (our boat with electric system weighs 495 lbs.)
* Remote steering connector option, comes with remote throttle.
* 23 hp gas equivalent
* 48 volt
* Weight 84 lbs.
* Speeds up to around 15 mph for at least an hour (on a 1,500 lb boat with the system and 2 people).
* Yamaha lower leg for easy part replacement.
* Water cooled.
* Motor Only price: $5,795  ($6.484 with shipping from Texas to California).

It are not using the Stealth NMC batteries due to their more volatile chemistry.  Instead, we plan to go with cheaper and safer DIY LifePO4 batteries we designed. The two LifePO4 batteries, all total, will cost us about $3,000, which is around $2,500 less than the Stealth package (motor plus battery).
The Steath E18KW only weighs 84 lbs. and our 230ah 48v LifePO4 safer set of two LifePO4 batteries weigh a total of 220 lbs.

The outboard requires 48v so that means we need two of our 24v batteries put in series.  Those plus the motor and tender weigh 505 pounds.  Our gantry lift system will be good for up to 600 lbs.  As for cost, it runs $3,000, total, for the two batteries and $6,484 for the motor totals $9,484.  That is an excellent price for an electric propulsion system. 

We should note that this electric system is still about double what a gas outboard would cost.  However, we do not wish to carry extra gas onboard the main boat, which adds weight and danger.  So, that extra cost is worth it to avoid those two issues.  Besides, this way we can refill our tender batteries from the main boat's batteries, which recharge from solar, sailing regeneration, or our diesel generator/engine (which is the last choice); therefore, we have endless 'fuel'.  Therefore, over time, the fuel savings will make up some of the extra purchase cost.  With gas running $5.00 a gallon, and figuring we will burn that much every five days over our 13 year double circumnavigation, that is a savings in gas of $4,745, making the cost of the electric system a about a push.

UPDATE: We have ordered the e18.  Sea trials and videos to begin in October, 2022.

Torqueedo 10.0 R

Torqueedo 10.0 R

* 12 kW peak power, 10 kW continuous power – powerful propulsion like a 20 hp combustion engine
* Simple handling thanks to voltage level of 48 V
* Recommended for dinghies and sailboats up to 10 tons.
* Remote steering connector option, comes with remote throttle.
* Intelligent on-board computer and all of the convenience of a Torqeedo electric drive system
* Very robust design – protected from corrosion, saltwater-capable, and completely waterproof (IP67)
* Low-profile design – elegant and modern
* 20 hp gas equivalent
* 48 volt
* Weight 132 lbs.
* Static thrust: 405
* Price $9,000 

Compared to the e18, we only get 10kw vs 18kw.  And, it would cost us an extra $4,400 and weigh 47 lbs more.

Elco

Elco EP-20

* Reliable and durable construction with minimal maintenance required
* Input Power: 8880 kW
* Traditional aluminum casting so replacement parts are readily available
* Water-cooled system that prevents over-heating
* Safety: over-speed protection, overload protection, temperature protection, over-voltage and over-current protection
* Consistent power throughout the speed range
* Brushless PMAC motor that is over 90-percent efficient
* “Get Home Safe” battery alert system
* 20 hp gas equivalent
* 48 volt
* Weight 85 lbs.
* Static thrust: 240 lbs.
* Price $4,804 

Compared to the e18, it is about the same price and weight, but this motor is only 8.889kw vs 18kw with the e18.

Aquawatt Green Power 15

Aquawatt Green Power E15.5 kW

* Controls: Tiller or single lever control
* Power input/output: 15.5 kW
* Transom height: 20 inch
* Nominal voltage: 48/50 V
* Current from battery max.: 320 Amp
* Weight: 115 lbs.
* Propeller size: 9.25 to 10 inch
* Static Thrust with thrust propeller: 275 lbs.
* Maximum speed: 23 knots
* Price: $8,220 

Compared to the e18, we only get 15.5kw vs 18kw and this motor costs $3,420 more and weighs 30 lbs more.

Aquawatt Green Power 22

Aquawatt Green Power 22 kW

* Controls: Tiller or single lever control
* Power input/output: 26kW / 22 kW
* Transom height: 20 inch
* Nominal voltage: 80 V
* Current from battery max.: 320 Amp
* Weight: 139 lbs.
* Propeller size: 9.25
* Static Thrust with thrust propeller: 337 lbs.
* Maximum speed: 26 knots
* Price: $16,732 

Compared to the e18, we get 22 kW vs 18 kW, which would be wonderful.   However, this motor costs about $10,000 more than the e18 and weighs an additional 54 lbs!   For the small amount of extra power, we might consider adding the weight, but that extra cost is not worth just 4kW of extra power (though we wish we had it).  Even if we were willing to pay the extra $10,000, the voltage is too high for our batteries.

ZeroJet

Zero Jet

* Controls: Tiller 
* Power input/output: 14kW / (19 hp)
* Nominal voltage: 48 V
* Weight: 85 lbs.
* Jet propulsion
* Price: $7,371.54 jet plus $7,371.54 proprietary battery (quoted NZD prices converted to USD).

Compared to the e18 at 22 kW vs  the ZeroJet at 14 kW, the e18 is 36% more powerful.  However, on the positive side, ZeroJet is a jet, so no propeller to worry about! 

Zerojet's website also claims they can build higher power systems, on request.  However, after contacting them, currently this turns out not to be true so they remain less powerful than the Stealth e18.  Unfortunately, a total price of $14,743 compared to the e18 total cost of $9,684 (motor and battery) makes the Zerojet option too expensive, $5,059 more while being 4kw less powerful.  The final straw is that it cannot be easily removed from the tender. 

Spirit 1.0 Plus

Epropulsion Spirit 1.0 Evo

 * Input Power: 1 kW
* Equivalent Horsepower: 3hp
* Motor Weight: 24 lbs.
* Battery Weight: 19.4 lbs.
* Battery Capacity: 1018 Wh
* Tiller Control
* Run time: 75 min to 4 hours, depending on power usage
* Range: 46.8 nautical miles at 2.3 knots or at full speed, 5.1 knots for 6.4 nautical miles.
* 48 volt (will also run off of our other battery pack).
* Price: $2500 

NOTE: The Spirit 1.0 Evo is a backup motor and will also be used when we want to beach the dinghy.  In that case, we remove the bigger main outboard and heavy batteries, shedding about 304 lbs, and go with just this small motor. The Spirit is waterproof, so if we get doused by a wave in the surf, that is no problem.  As a backup to the main motor, the Spirit can also be brought on board, without its attached battery.  Without the attached battery, it only weighs 24 lbs.  In an emergency, the Spirit can be mounted to the transom and plugged into the same 48v battery bank that the larger outboard motor uses.  And though the trip might be slow at 5 knots, it would get us back to the mothership to make repairs to the bigger tender motor.

There is a new feature with the Evo model, they have added hydrogeneration.  Of course, this is a small amount of regeneration; at maximum, we will be getting around 300 - 330 watts an hour.  Still, if we mount this to a sugar scoop while on passage it will send around 150 amps per day to the main battery.  That is enough for all house needs for a day.  So we can use it when the batteries are nearly full instead of our two 25kw motors, either of which add a lot of drag when regenerating.  That way, the much lesser drag of the Evo can still supply enough power to run things like chartplotters and radar, etc. without slowing the boat much.  We can use the big motors for regeneration when we need to recharge the main battery more swiftly.

Update: We have placed our order for our Spirit 1.0 Evo with sea trials and videos to begin in October, 2022.

Our conclusion on tender motors

The choice is fairly clear and we based our winner on the power of the motor and cost to purchase, so the Stealth E18 is our choice!  In fact, we ordered one!  We have also purchased an ePropulsion Spirit 1.0 Evo for trips through the surf and as a backup motor to the E18 to get us home in a pinch.

Here is a wall of text if you want to know more about our choice of outboards:

Based on what we have learned, we went with the Electric Propulsion for our tender. 

Note, if we were running a straight diesel catamaran, instead of a combo hybrid diesel/electric, we might have made a different choice (gas).  However, this electric outboard's batteries can be charged by our existing electrical system on the main boat. There, we will have over 5 kw of solar panels, two 20 kw electric motors for regeneration, and a 10 kw 48vdc generator.  Between these systems, we can easily charge the main batteries of the big cat and and the second bank of tender batteries. Therefore, an electric propulsion system on our tender just makes the most sense since we won't have to cart around, find, or purchase flammable gasoline.  On long voyages, when we won't need to use the tender, we can tie the tender batteries into the main boat and increase by 1/3 to 690ah at 48vdc available for house and propulsion needs.

Gas motors have a farther range on one excursion, but far less excursions possible, let us explain:  

1) Farther range on one excursion: Gas is more energy dense than batteries.  Therefore, a gas engine will take you much further on a tank of gas than electric will on a similar weight in batteries.  However, it should be noted that with an electric motor, you may sacrifice speed for distance.  Our tender, with its electric outboard, will likely travel 7 miles when going 15 mph before depleting the batteries.  However, if we slow down to 7.5 mph, it will takes us a lot further, up to eight times the range.  Of course, that is in a perfect world.  Yet, even if it only goes half that far, we could travel 28 miles.  Therefore, we should always have sufficient power to get us back to the main boat.  Besides, we never plan to be that far away (more than 10 miles or so).

2) More excursions: Consider this, there are times when you will want to make multiple runs over many weeks, like when you are in the remote Tuamotus Islands for two months.  If you are running a gas powered tender every day, you will eventually run out of gas.  If you carry extra gas on board your main boat, that is extra weight and a flammable fuel on board.  However, with electric propulsion, you will always have sunlight to recharge the batteries form solar panels, giving you endless supplies of fuel for additional runs.

As for when we have heavier loads in the dinghy, in the tests for the Stealth motor, the boat weighed 1,500 pounds, and they added two people (360 lbs.).  That means, if you total the boat, propulsion system, and passenger weight, you get 1860 pounds.  Even with all that weight the test boat still did 15 mph on a plane.  A light weight RIB tender, with electric outboard and batteries, weighs 500 pounds.  If we add two average people, weighing 180 pounds each, we are at 860 pounds.  That still leaves 1,000 pounds available!  That means, we should easily get 4 divers and dive gear to a dive site since that total weight would be less than the LCC of this boat and engine, three hundred pounds under the target weight.  Or we can take seven people (1260 lbs.) and add the boat and we are at 1739 pounds, still under the target weight of 1,860.

Now, their test was done in an ideal situation, on a lake with flat water.  Still, if our 18kw of electric propulsion outboard can get our tender up on a plane with six people (1080 lbs.) we will be quite happy.  Time will tell as we have the purchased the motor and will be doing sea trails soon!  Keep an eye on our Youtube channel for those.


Dinghy Chaps

What are Dinghy chaps for?

Chaps
With Hypalon material tubes dinghy's can last about 10 years even in harsh tropic sun conditions. However, that doesn't mean they won't start to look a little dull and worn out over time.

Also, abrasion from lines or other things, like dragging scuba gear in and out, can damage the hypalon.

To the rescue come dinghy chaps!  These are a cover you put over the tops of the tubes to protect them from abrasion and UV damage. With Chaps, we hope to extend the life or our dinghy for the entire double circumnavigation.

Dinghy Chaps

Where can you get chaps?

Where do you get chaps?
Unfortunately, due to variances in the locations of mounts and other protrusions, dinghies are not exactly the same.   Therefore, chaps are not mass produced. That leaves two ways for us to get Chaps:

1) Hire someone, or a company, to custom make the Chaps by letting them have our dinghy for a time while the Chaps are created.  This typically costs $2,000 or more!

2) Make them ourselves. Though far less expensive, this option does require us to own a sewing machine capable of sewing through multiple layers of thick UV resistant materials.  However, we already plan to purchase such a machine for sail repairs and other needs.  So, now it is just down to the knowledge and labor of sewing these chaps.  Fortunately, there are 'how to' videos available, so that covers the knowledge, so we just need to set aside the time.  Fortunately, two of our crew members are good at sewing!

Chaps

Boat Wheels

Why do you need boat wheels?

These help you pull a relatively heavy dingy up onto a beach by letting wheels take up a large portion of the weight.  The wheels are mounted to the outside of the dingy transom.  When not in use, they can be retracted upwards so that they don't drag in the water.  When approaching shore, the wheels can be extended down so that you are ready to pull the boat up on to the beach.

Here is our choice for boat wheels for our dinghy:

BeachMaster

* The Patented BEACHMASTER Autolock system is light and strong as well as being extremely fast, easy and clean, and may be operated without touching the wheels.
* Beachmaster boat wheels unique over-center locking mechanism compactly encapsulates and locks the wheel against the transom when retracted, then extends in use to form a cross braced frame for high strength in all directions.
* They are designed to be used with outboards in shallow water drive mode so they can be operated close to shore.
* Their very fast and easy to use auto-locking action up and down is an essential feature for launching and landing on surf beaches and fast flowing rivers or when conditions afloat are rough.
* A reassuring click instantly lets you know the wheels are securely locked home in both the up and down positions.
* The retracted wheel is locked and prevented from spinning which provides a secure handhold for safety when working around the outboard.
* The easy to reach non-jamming up-and-away motion of the mechanism enables the wheels to be deployed and retracted in the shallowest possible water. Beachmaster dinghy wheels are not jammed by the buoyancy of the tire or grounding as can be the case with other systems. 

BeachMaster 1

* The low visual profile and compact retracted position of beachmaster dinghy wheels against the transom allows for normal unhindered operation the boat and outboard motor.  The wheels are quiet and smooth running and are large, quality, Nylon reinforced, 4 ply rated pneumatic tires (10.5" diameter) with polypropylene rims and nylon bearings for durability in marine environments, using Butyl tubes for reliability.
* Being self contained there are no separate parts to stow or lose or pins to fit. They are always instantly ready for action.
* For strength, durability and light weight the wheel system is manufactured with marine grade boat building Aluminum.
* The mounting bracket measures 5.5" x 8" and is effectively designed to distribute the wheel loads to 4 widely spaced bolts. 

BeachMaster 2

Specs on the BeachMasters

    * Recommended for boat lengths up to 12 feet. (3.6 m) [ours: 12'6"]

    * Recommended for gas outboards up to 15 hp which weigh about 85 pounds. Our electric outboard is: 20 hp, but it only weighs 85 pounds, but more of the time we are beaching the boat we will be using our 3 hp, 43.4 ePropulsoin Spirit 1.0 Evo!

        * Maximum load limit 440 lbs (200 kg)/set on hard smooth surfaces for both fixed and removable mount types.   Our heavy version of the dinghy weighs: 505 pounds, but we would rarely, if ever, be on the hard with our dinghy in this heavy configuration, mostly we would weigh 244 pounds.

    * Recommended tire pressures 5psi (soft surfaces) to 15psi (hard surfaces).

    * Mount Weight: 10.5 pounds (4.8 kg) per set of two.

Conclusion on Tender Wheels


We looked at all the options for wheels to beach our RIB and the clear choice for quality and function are the Beachmaster wheels.  Their is even an option for a removable mount, which we will choose as it offers us some options in configuration.  We will post a sea trial and video review of the Beachmaster Wheels once they arrive from New Zealand, hopefully in October, 2022.

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