Dinghy & motor-gas or electric

[Porchhound]

Going to need a dinghy. I'm no longer the spry, athletic lad I remember. I had an inflatable fifteen years ago with oars but it was tricky to enter and exit from a sailboat. The cruiser we're considering has a swim platform and a transom door...so that should be easier, even with a big rubber duck of a dinghy. Anyone use anything else other than an inflatable, and is it easier to get in and out of?

Second question has to do with power...gas or electric? Combined we weigh about 350lbs (after lunch). I've read some online articles but they're pretty much all over the place.

NOTE: Suggestions on dieting will be met with an insolent stare.

 

[Larry M]

I leave the dinghy type to others but as far as a motor goes how are you going to use it? As just a shore tender, electric would be fine as long as you have a way to charge it.

We always had gas. Our dinghy was our pickup truck/car and was also used it for provisioning. We’d regularly live at anchor 6 plus months a year. We did a lot of exploring and doing it on a plane was important. It wasn’t uncommon to travel for several hours a day based on location.

 

[Porchhound]

In the past we used ours mainly for trips to shore, or an occasional gas run for the old atomic four engine. Good questions. We'd probably do more exploring now because we have more time.

 

[DavidM]

I don't know of any type of tender that is more stable than an inflatable. I once used a little twin hull fiberglass dinghy. It was much less stable than an inflatable.

Whether an electric o/b is suitable depends on how far you go and the means you have of recharging it.

David

 

[ranger58sb]

Second question has to do with power...gas or electric? Combined we weigh about 350lbs (after lunch). I've read some online articles but they're pretty much all over the place.

They're probably "pretty much all over the place" because the way people use dinghies is so widely varied.

I wanted to go electric this time, but... I also want to be able to plane a console tender. Well, 20-hp electric outboards exist, but... the "fuel" -- a lifetime of it, purchased all up front -- either weighs a boatload (AGM batteries for a 48VDC system) and/or costs an arm and leg (lithium plus BMS).

IOW, no savings over gas (aside from issues with gas and ethanol and so forth) and potentially even more expensive.

But back to your issue: depends. (Useful, eh?)

But generally if you can putter and/or limit distance, electric has attractions. If you need to plane and/or travel longer distances, back to gas.

I've found inflatables and RIBs to be more stable than rigid dinghies, and that's a big deal for wifey. They usually don't row for squat.

The dinghy needs it own ecosystem: motor, weight, fuel, battery?, how to store (boat and motor separately or together?), how to launch, how to recover, etc.... and your swim platform may or may not be rated to carry the dead weight, so may need reinforcement... so all that is best solved (or at least addressed) during your shopping phase.

-Chris

 

[JLD]

I would likely choose electric with an extra battery, if this works for your needs. Advantage is you don't have yet another fuel type (gas) to keep on board.

Jim

 

[DDW]

It is really the difference between planing and not. If you don't have the need for planing capability, then an electric does nicely - really no need for spare batteries and all that. They are easy to charge from usual onboard sources, and in average dinghy use you'll only need to do it once a week. Living aboard with daily trips to shore or puttering the anchorage we go 1-2 week between charging.

 

[FWT]

Going to need a dinghy. I'm no longer the spry, athletic lad I remember. I had an inflatable fifteen years ago with oars but it was tricky to enter and exit from a sailboat. The cruiser we're considering has a swim platform and a transom door...so that should be easier, even with a big rubber duck of a dinghy. Anyone use anything else other than an inflatable, and is it easier to get in and out of?

Second question has to do with power...gas or electric? Combined we weigh about 350lbs (after lunch). I've read some online articles but they're pretty much all over the place.

NOTE: Suggestions on dieting will be met with an insolent stare.

I'm shopping (for a new build in process), so I don't own one yet. But you open the door to a non-inflatable. IE a hard dink.

Most hard dinks have round chines and while quite safe and have other good attributes, the round chines results in soft edge stability as you step aboard. Those more nimble have no big issue learning to step well in, with weight coming down more in the centerline of the boat. Guests and some others might not "get it" or find that less than desireable.

An exception I am looking hard at is the Whaly. They come in a series of sizes. The designs are basically like an inflatable but made of hard plastic. But with the added benefit of having seats molded along the "tubes". Result is you need not step deep into the boat, need not step over the tubes, but rather onto the seats a scant few inches from the edge of the boat, and appear to have the edge stability it seems you want. They can carry a lot of weight for their size, most likely 750 pounds or more for the sizes you will likely choose.

A downside was pointed out on this site recently. Its made of plastic, and it seems the transom has a bit too much flex for a gas outboard big enough to get up on plane. Fine for an electric (which I plan to get).

I will be using a davit crane to carry it up top. There are no purpose-built attachment points for a lifting bridle but I think I have mostly figured that out. I have not explored how you might install davit attachment points to carry off the swim platform, but you can reach out and ask them.

So bottom line is, if you want speed and a gas outboard, an inflatable RIB is likely the path. If a slower speed electric appeals, then this might be an option.

https://www.whalyboatsusa.com/

 

[Porchhound]

Lots of good info and food for thought, thanks. I'll check out that link.

 

[TBill36]

A few things to consider.
- As mensioned, you will probably end up using it much more than you anticipate. The more confident you are in your dinghy, the farther you will go and explore. We spend countless hours doing such.
- So, exploring etc means longer distances and you want to be able to plane so consider this in your decision.
- Seating comfort is a biggy for me. My back can't take sitting on the side and twisting the throttle. A cooler in the center works, but a small center console is better.
- Do yourself a favor and get a bimini top. Very inexpensive on line and I can not do without one now that I've had one.
- How will you store it. Taking a motor on and off is a PITA and eventually you are going to drop it. Lifting the dingy with motor attached onto the boat is the best option. followed by tilting it up on the dive platform, and least attractive is towing it. Towing can be considered dangerous in some conditions.
- An inflatable doesn't need bumpers when tying up.
- A hard bottom RIB is most desirable as it can handle a chop and small seas better than a soft bottom.
- At least 10 ft if you can store it and the bigger the better.
To me the dinghy decision is one of the most important aspects of boating if you plan on cruising and anchoring out.

 

[Iggy]

My next motor for the inflatable, I "think" will be propane? Not sure on that, but no gasoline to go bad or clog the carburetor. And still have the power of a gasoline motor with a cheaper price tag.

 

[High Wire]

A 6 hp or less four stroke ob will have manageable weight but if you are going to put it on and off daily then 3.5 hp or electric.

 

[backinblue]

I have had both and am now electric and it has many advantages over gas. However, I think you should first think about the dinghy. If it's a small inflatable that needs 4 HP or less, electric is almost a no-brainer. If you have a dinghy where you want or need 10-15 HP, you are probably still best with gas. Speaking of gas, the 4 strokes are quite a bit bigger and heavier than their 2-stroke counterparts. A 4HP 4-cycle motor is still more weight than I want to be lifting on a regular basis.

 

[rslifkin]

The weight thing is key. Outboard options are very different if you have to take it on and off every time vs if the dinghy is stored in a way that the outboard can stay on.

 

[backinblue]

The weight thing is key. Outboard options are very different if you have to take it on and off every time vs if the dinghy is stored in a way that the outboard can stay on.

To that point, that was a big difference to me with electric and lifting it on and off the dinghy from the swim platform. The gas motor might be 45 lbs and the electric 35 lbs, BUT the electric breaks apart into the motor and the battery, each piece under 20 lbs, so my wife can single-hand them to me. That and never having to struggle for either of us to start the motor made a world of difference. If she wants to go off by herself to the beach, I don't have to worry if she'll have trouble starting the motor. More than enough range for how we use it.

 

[Nomad Willy]

I would use gas power if for no other reason but lightness.
Re the dink there are 10 and 11’ aluminum skiffs that are very light. Some are super light .. made w lightweight aluminum (thinner).
Not an excellent rowboat w their transom down in the water. However you can row them and better that most any kind of inflatable.
And they can run 8-10 knots w far less power that any ducky. Think 5hp.
And they comparatively last forever.

 

[backinblue]

I would use gas power if for no other reason but lightness.
Re the dink there are 10 and 11’ aluminum skiffs that are very light. Some are super light .. made w lightweight aluminum (thinner).
Not an excellent rowboat w their transom down in the water. However you can row them and better that most any kind of inflatable.
And they can run 8-10 knots w far less power that any ducky. Think 5hp.
And they comparatively last forever.

Hi Eric. Not sure why you think gas motors are lighter than electric and last forever. That has not been my experience with the new LiPo powered electric motors. They also require zero fuel and zero maintenance. Just need a way to charge them.

 

[rslifkin]

The lightest gas engines are a hair lighter than the lightest electrics, but the electrics split into 2 parts (battery and motor). I'm seeing 34 lbs for the smallest Torqeedo model, 27 lbs for the 2.3hp Honda and 2.5hp Suzuki. The Torqeedo claims "2hp equivalent", but that's based on thrust at low speeds, it doesn't actually produce 2hp. So the gas engines do still have a better power/weight ratio at this point, but that will continue to change.

 

[psneeld]

The big question is how long will that battery last?

The biggest decision is how fast/far do I want to go even just some of the time?

I just priced out a comparable electric to a 9.9 gasser for a skiff...at least 3X the cost.... $10K vs $3k..... the battery alone was almost $5K.

Sure there will be prices that vary...what about 4 years from now, and the battery is no longer availabe like so many battery powered tools through the years?

Tough decisions...I would love to go electric but not with current costs and unknown battery availability....even though I know I could jury rig something.

 

[backinblue]

I would recommend you take a look at this instead of Torqeedo. Claimed 3 HP eduivalent at 44 lbs. But since the battery is 20 lbs, the heaviest piece you are dealing with is 22 lbs. A 3.5 Merc is 41 lbs.

https://www.epropulsion.com/spirit-evo/

 

[backinblue]

The big question is how long will that battery last?

The biggest decision is how fast/far do I want to go even just some of the time?

I just priced out a comparable electric to a 9.9 gasser for a skiff...at least 3X the cost.... $10K vs $3k the battery aline was almost $5K.

Sure there will be prices that vary...what about 4 years from now, and the battery is no longer availabe like so many battery powered tools through the years?

Tough decisions...I would love to go electric but not with current costs and unknown battery availability....even though I know I could jury rig something.

I tend to agree that right now, only the smallest outboards make sense in electric, but that will change before long.

 

[rslifkin]

I would recommend you take a look at this instead of Torqeedo. Claimed 3 HP eduivalent at 44 lbs. But since the battery is 20 lbs, the heaviest piece you are dealing with is 22 lbs. A 3.5 Merc is 41 lbs.

https://www.epropulsion.com/spirit-evo/

They pull the same crap as Torqeedo with the claimed HP equivalents. 1kw of power is not 3hp in any universe. At best, it's about 1.3hp. They're basically saying that it makes the same peak thrust as a 3hp gas outboard, not that it actually outputs 3hp.

 

[ranger58sb]

The big question is how long will that battery last?

The biggest decision is how fast/far do I want to go even just some of the time?

I just priced out a comparable electric to a 9.9 gasser for a skiff...at least 3X the cost.... $10K vs $3k..... the battery alone was almost $5K.

Sure there will be prices that vary...what about 4 years from now, and the battery is no longer availabe like so many battery powered tools through the years?

Tough decisions...I would love to go electric but not with current costs and unknown battery availability....even though I know I could jury rig something.

Yeah. I'd hoped for an Elco 20-hp outboard, but...

Either the battery bank would weigh around 380 lbs (4x G31 AGMs at 48VDC) or it would cost north of $3500 or some such (LiFePO4, can't remember exact numbers).

-Chris

 

[backinblue]

I get it. You can argue hp/thrust/torque etc, but in the end does it really matter? If the electric motor provides the equivalent performance of a 3 HP gas motor, does it really matter what numbers you want to plot on a graph? They don't claim it outputs 3 HP, they say it is equivavlent to a 3 HP gas motor, meaning it can replace a 3 HP in most applications.

 

[rslifkin]

I get it. You can argue hp/thrust/torque etc, but in the end does it really matter. If the electric motor provides the equivalent performance of a 3 HP gas motor, does it really matter what numbers you want to plot on a graph?

The thing is, it's not necessarily equivalent to a 3hp gas motor. It may produce the same peak thrust, but likely at a lower speed. So it'll push a heavily loaded dinghy as well as a 3hp gas motor at low speeds (and may do a better job of accelerating from a stop), but because hp is a measure of work done over time, the motor that's actually 3hp can do more work (in other words, assuming both setups are propped optimally, etc. it'll push the same dinghy faster).

The proof of this issue comes in looking at the data given for the bigger e-propulsion outboards. They list their biggest as 6kw / 9.9hp. But 6kw is only about 8hp (assuming perfect efficiency, so power at the prop will be less than 8hp and gas outboards are rated at the prop). They show it pushing a 12 foot aluminum boat to 15 mph with 1 person on board. 9.9 actual horsepower at the prop should get that setup to 20 mph.


Not to say the electric outboards are bad or anything. I just hate the way they advertise them to make them sound more powerful than they really are.

 

[psneeld]

I tend to agree that right now, only the smallest outboards make sense in electric, but that will change before long.

To get the power and duration...battery tech has to enter a whole new generation.

Sure tech change is accelerating.....not sure that "before long" adequately describes how long. My guess is at least 10 years till you see batteries with enough capacity to drive 10 and more horsepower for hours and power dense enough to be as small as a 3 gallon gas can.

 

[backinblue]

The thing is, it's not necessarily equivalent to a 3hp gas motor. It may produce the same peak thrust, but likely at a lower speed. So it'll push a heavily loaded dinghy as well as a 3hp gas motor at low speeds (and may do a better job of accelerating from a stop), but because hp is a measure of work done over time, the motor that's actually 3hp can do more work (in other words, assuming both setups are propped optimally, etc. it'll push the same dinghy faster).

The proof of this issue comes in looking at the data given for the bigger e-propulsion outboards. They list their biggest as 6kw / 9.9hp. But 6kw is only about 8hp (assuming perfect efficiency, so power at the prop will be less than 8hp and gas outboards are rated at the prop). They show it pushing a 12 foot aluminum boat to 15 mph with 1 person on board. 9.9 actual horsepower at the prop should get that setup to 20 mph.


Not to say the electric outboards are bad or anything. I just hate the way they advertise them to make them sound more powerful than they really are.

I don't disagree with you. However, I doubt anyone is buying a 3 HP motor for top-end performance. So in your example, if you have 2 people and some gear in a dinghy and need to travel at 5 MPH to shore, I could argue that they are equivalent in performance. You are not going to be on plane with either motor. And if that is your normal use-case, electrics have a lot of other advantages.

 

[ABfish]

I've recently become an electric chainsaw convert. It's quiet, it doesn't stink, it doesn't require pull starting and I don't have to carry a container of gasoline in my truck. It still needs bar oil, though, so you're not completely separated from petroleum products.

On the other hand, it's no lighter than a comparable gas saw and you need to carry an extra battery for extended use.

I think the comparison to the dinghy motor are valid. I still have a commercial duty Stihl chain saw, but for many chores the electric is more than adequate and easier and quicker to use.

 

[Shrew]

We use our dinghy way too much to go with electric. The last thing I want is to be sitting around waiting for the batteries to be recharged.

 

[rslifkin]

I've recently become an electric chainsaw convert. It's quiet, it doesn't stink, it doesn't require pull starting and I don't have to carry a container of gasoline in my truck. It still needs bar oil, though, so you're not completely separated from petroleum products.

On the other hand, it's no lighter than a comparable gas saw and you need to carry an extra battery for extended use.

I think the comparison to the dinghy motor are valid. I still have a commercial duty Stihl chain saw, but for many chores the electric is more than adequate and easier and quicker to use.

For something like a chainsaw, string trimmer, etc. I think the advantages of electric are even bigger. The smaller you make a gas engine, the more finicky it gets. And those are also equipment that tends to get used sporadically and spends a lot of time sitting. Electric stuff is much easier to keep working properly with infrequent use.