Dinghy Motor

I am replacing our old dinghy with, I believe but not yet purchased, a new Highfield 290 CL RIB. Aluminum hull, Hypalon, 9'6", 126 lbs. DInghy use is ship to shore, no long excursions. I need to find a motor for it that I can take off the transom when we are done and store it either laying down in the dinghy or on some sort of bracket nearby. Day in day out use is for me, my wife, and a 70lb dog. Max load, on rare occasions would be 4 adults for a short trip to shore. Don't really care about being able to get up on a plane.

I have looked at the electric motors, E-Propulsion and Torqeedo, and they do look inviting for all the well-known reasons but....I don't know. I don't need to go fast but need to go 5 mph at least.

I think I am more sold on a small outboard, preferably with an internal gas tank, an oil/fuel containment system so I can lay it down, and light enough to be able to take on and off either in the water or on deck after lifting it up. Lifting 100lbs in my garage is one thing. Doing it in the back of a dinghy is another.

Does anyone here have a motor of this type? Any suggestions, thoughts?

For your use I would really suggest the e-Propulsion Spirit with the shortest shaft available.

I switched my Suzuki 2.5hp for one and it's night and day a better experience - silent operation, no starting issues, no freshwater flush, no maintenance, a throttle that goes backwards and forwards versus spinning the motor around, etc. etc.

To get more speed than the e-Propulsion you'd need something bigger than the 2-3hp engines. I don't even know if a 6hp would do it - you're probably looking at 9.9hp, which means no integral fuel tank, and 85lbs+. The 4-6hp engines I see don't have an integral fuel tank, weigh 50lbs+ and wouldn't get your dinghy on a plane with any load most likely, so you're at the same speed as the electric anyway.

Main disadvantages of the electric are limited range & power/speed - neither appears to be an issue for you. Not having any gasoline aboard is really nice too.

firstbase said:

I have looked at the electric motors, E-Propulsion and Torqeedo, and they do look inviting for all the well-known reasons but....I don't know. I don't need to go fast but need to go 5 mph at least.

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You might also have a look at Elco electric outboards. Interesting, on paper, no first hand experience...

-Chris

My vote would be for a used 5 hp or less 2 stroke gas OB. As a previous owner, a 4 hp Evinrude 2 stroke from the 70's weighs in at about 35 pounds with an internal gas tank. 32 with an external 3 gal tank. A 6 hp Evinrude weighs 56 pounds. A 7.5 weighs the same and will plane off a 9.5' dinghy.

socalrider said:

For your use I would really suggest the e-Propulsion Spirit with the shortest shaft available.

I switched my Suzuki 2.5hp for one and it's night and day a better experience - silent operation, no starting issues, no freshwater flush, no maintenance, a throttle that goes backwards and forwards versus spinning the motor around, etc. etc.

To get more speed than the e-Propulsion you'd need something bigger than the 2-3hp engines. I don't even know if a 6hp would do it - you're probably looking at 9.9hp, which means no integral fuel tank, and 85lbs+. The 4-6hp engines I see don't have an integral fuel tank, weigh 50lbs+ and wouldn't get your dinghy on a plane with any load most likely, so you're at the same speed as the electric anyway.

Main disadvantages of the electric are limited range & power/speed - neither appears to be an issue for you. Not having any gasoline aboard is really nice too.

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Thanks. When looking at the electrics I did narrow it down to the e-Propulsion based on several features, a higher watt battery being one. What size dinghy did you put yours on?

ranger42c said:

You might also have a look at Elco electric outboards. Interesting, on paper, no first hand experience...

-Chris

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I did review those as well. I don't remember the exacts but I crossed them off due to a couple of factors. They've been in business quite a while. The only negative comment I have read or heard on the e-Propulsion is that "they are the new kid on the block".

I cannot speak to the "electric motors" first hand, but recharging, battery life (including how long it will operate on one charge after it ages a bit), etc. would be concerns for me.
I had a Nissan 6hp 4 stroke motor for a few years. It would plane my similar dinghy to what you describe with just me in it, but when my wife joined me, it would not plane. It was unreliable due to gas "storage" (could not seem to completely eliminate the gas from the engine for winter storage) and developed starting and stalling issues.

I moved to a Yamaha 8hp 2 stroke. It weighed about the same, only had oil in the leg (which did not leak), and the dinghy would plane with both of us in it. Very reliable engine, starting on the 2-3rd pull after winter storage and 1 pull most other times. If memory serves, it weighed about 80 lbs and I could handle it without tooo much trouble. You could also install an "engine davit" on one of your rails to make engine handling a bit easier??
Mixing gas is easy, and I highly recommend the Yamaha 2 stroke. It would have to be used, as they no longer make 2 stroke. Unless things have changed greatly, I do not recommend any 4 stroke small outboards (less than 9.9hp) due to potential "fuel" issues like I experienced. FYI. I did ALL of the recommended maintenance, procedures, used fuel stabilzer, etc. and still had regular problems with the carb requiring complete disassembly every year.

firstbase said:

Thanks. When looking at the electrics I did narrow it down to the e-Propulsion based on several features, a higher watt battery being one. What size dinghy did you put yours on?

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Ours is on an Achilles HB-315LX 10'6" dinghy.

Those old 2-strokes are power/weight champs for sure but they pollute the water and air terribly.

A little dink two stroke does NOT "pollute the water and air terribly". The trace of oil and fuel out the exhaust is so minimal and is readily consumed by organisms naturally in the sea.

Absolutely and issue if there are hordes of old 235hp OMC two strokes running all over the place burning 20gph each. But we are talking little dinks that might burn a couple gallons a YEAR.

The little two strokes are really the dink champs. I tried a four stroke and it was heavy as heck and the carb finicky as heck as well. Nice cleaning the carb on my galley countertop in the Bahamas. That was a Yamaha 4s single cylinder. Good motor but in many ways it made me grumpy.

The little Yamaha 2s 2cyl are really champs. Like 6 to 9.9hp. Light and reliable. I now have an 8hp two stroke Merc (really a Tohatsu) and it also a champ. Almost 20yrs old and just this morning towed a skiff that sank (and we refloated) on my dock, the merc did not miss a lick. But the old 2s motors available in the states are getting long in the tooth, so there is that.

If you go to the Bahamas or Mexico, you can buy brand new Yamaha two strokes.

The electric option is really appealing if you know your will never travel very far. I could do electric for 95% of my dink trips. That remaining 5% makes is a bugger.

The OP's question will generate a million opinions and reignite the debate over gas and electric - and I'm sure there are multiple past threads on the same topic. For what it's worth though, for our 10 foot inflatable, we use a 4HP Yamaha two stroke. Can't pull a water skier for sure, but does okay with two adults, two kids and a small dog. Weighs about 50 lbs - wish it were lighter, but I can still lug it around and hang it on a bracket on the aft deck for long runs when we flip the dingy over on the bow of the mothership. I bought that motor (4SH, vintage 1980's) in a guy's grassy backyard in Clinton, CT in 2015 for a peanut price. Still easy to get parts and runs smooth after all these years. I have cleaned the carb gaskets twice in six years, but not a big deal. Pretty darn good for a motor that's coming up on 40 years old, and spent most of its life in saltwater.

Ski in NC said:

A little dink two stroke does NOT "pollute the water and air terribly". The trace of oil and fuel out the exhaust is so minimal and is readily consumed by organisms naturally in the sea.

Absolutely and issue if there are hordes of old 235hp OMC two strokes running all over the place burning 20gph each. But we are talking little dinks that might burn a couple gallons a YEAR.

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Old 2 strokes are nasty for a bunch of reasons - of course bigger ones are proportionally worse than smaller ones. Newer EFI 2-strokes are somewhat better, but there's a reason the old carbureted 2-strokes are banned most places now. About 25-30% of the fuel is not burned and goes into the water - think about that whenever you fill the tank. Moreover, the combustion byproducts are way worse & persist for a long time.

https://www.sciencedirect.com/science/article/abs/pii/004313549400331Z

In remote areas I might buy your argument that this pollution is so diluted as to not matter, but in the areas where a lot of us cruise, which are already under heavy environmental stress, I don't think it's conscionable to use this technology if you have the means to buy something better. Again, there's a reason these engines are banned.

I have had a Torqeedo for years. For running back and forth from boat to shore, it really can’t be beat. If that is the extent of your use, I would strongly encourage you to consider an electric. Lightweight, easy to store, never have to carry gasoline on board, virtually no maintenance, quiet…

We are getting a new RIB and since we want some added speed for certain types of exploring, we are doing to go with a larger RIB with a 20hp motor. Having said that, if we were still looking for something to go from anchor to shore only, I would stick with the Torqeedo. It also is great for motoring around an anchorage or harbor where no-wake zones or common courtesy limits you to 3-4 knots anyway.

We have the littlest 2 hp 4-stroke honda makes. We bought it because of the weight, not because I gave too much thought about how much it pollutes. I've owned over a dozen 2-strokes over the years and never had to worry about draining the carburetor. With this 4-stroke I have to drain the carb regularly. I dump the gas in the driveway to kill weeds because I'm not sure where to get an approved container for old gas.
The planet will be ok because it's got a big sticker on the cover that says it has a 3-star California rating.

For the carb issues, I've found a method that's been working so far on my small lawn equipment 4 strokes to avoid the cheap, crappy carbs gumming up. The same should apply to small outboards.

All fuel is stabilized immediately at purchase. Never, ever run the carb dry, that way it doesn't accumulate a thin film of evaporated fuel gunk or get condensation directly against metal in as many places. And if it's going to sit for more than a few weeks, run fogging oil through the intake at shutdown so the inside of the carb is good and oily, further preventing corrosion and gunk issues.

Nice tip rslifkin! I’m gonna try that…makes sense.

socalrider said:

Old 2 strokes are nasty ...About 25-30% of the fuel is not burned and goes into the water...

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That can't possibly be right, even if there is a link to a scientific paper attached. Let's see, test engine was 15kw, that's what, about 20 HP, so bigger than most dingy motors, but okay let's go with that -- so they concluded that after one hour that motor polluted -- 11,000 cubic meters of water?!? That's 2.9 million gallons! And 30% of the fuel goes into the water? Come on now. If that were really the case every very busy marina or weekend launching ramp would eventually burst into flames, stink like an oil refinery, have a bright gas sheen on the water and fish carcasses would be floating everywhere.

I used a Honda 2 HP 4-stroke for years on my 9.5 ft Achilles with 15 inch tubes. It was fine for boat to shore and marina cruises. I'd go 5 mph at 1 gph...best boat efficiency I'd seen. Unfortunately, the Honda 2 is air-cooled and noisy, especially at higher RPMs. OTOH, it only weighed about 27 lbs.

The Achilles was a wet ride in anything over 1 ft waves. Sometimes it got so bad I'd have to hide behind my fwd passenger!!

I upgraded to a 3.3M with a 15. Much drier, faster and safer now and I don't need to hide behind the fwd pass as often. But I still cling to that ol' Honda 2 as my backup dink motor. Love that thing!!

If I had room, I'd mount it as a kicker motor for my dink.

FlyWright said:

Unfortunately, the Honda 2 is air-cooled and noisy, especially at higher RPMs. OTOH, it only weighed about 27 lbs.

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For this reason alone, if you want a tiny dinghy engine, I'd take the current Suzuki 2.5 over the Honda 2.3 any day. The Honda is air cooled, the Suzuki is water cooled and significantly quieter (plus slightly cheaper). Both weigh 29 lbs in the short shaft version.

rslifkin said:

For this reason alone, if you want a tiny dinghy engine, I'd take the current Suzuki 2.5 over the Honda 2.3 any day. The Honda is air cooled, the Suzuki is water cooled and significantly quieter (plus slightly cheaper). Both weigh 29 lbs in the short shaft version.

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I agree completely...but there's also the lower maintenance without an impeller. That also matters to some folks.

The Honda has an interesting centrifugal clutch that only turns the prop when throttle is applied. The ladies of my family loved driving with that feature years ago.

FlyWright said:

I used a Honda 2 HP 4-stroke for years on my 9.5 ft Achilles with 15 inch tubes. It was fine for boat to shore and marina cruises. I'd go 5 mph at 1 gph...best boat efficiency I'd seen. Unfortunately, the Honda 2 is air-cooled and noisy, especially at higher RPMs. OTOH, it only weighed about 27 lbs.

The Achilles was a wet ride in anything over 1 ft waves. Sometimes it got so bad I'd have to hide behind my fwd passenger!!

I upgraded to a 3.3M with a 15. Much drier, faster and safer now and I don't need to hide behind the fwd pass as often. But I still cling to that ol' Honda 2 as my backup dink motor. Love that thing!!

If I had room, I'd mount it as a kicker motor for my dink.

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I've never measured the fuel consumption of our honda 2 but I don't think it's more than a quart an hour! I carry an extra gallon but never had to use it.

kthoennes said:

That can't possibly be right, even if there is a link to a scientific paper attached. Let's see, test engine was 15kw, that's what, about 20 HP, so bigger than most dingy motors, but okay let's go with that -- so they concluded that after one hour that motor polluted -- 11,000 cubic meters of water?!? That's 2.9 million gallons! And 30% of the fuel goes into the water? Come on now. If that were really the case every very busy marina or weekend launching ramp would eventually burst into flames, stink like an oil refinery, have a bright gas sheen on the water and fish carcasses would be floating everywhere.

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It's shocking I agree - but it's also true. If you think of how a 2-stroke works it makes sense - the engine has to exhaust burned HC's and intake a fresh charge at the same time, so much of the fuel/oil/air mix intake charge "short circuits" straight through into the exhaust. Here are two more sources:

1973 Penn State peer reviewed: 25-40% https://www.jstor.org/stable/44716338
1999 Vermont study: 20-30% https://anrweb.vt.gov/PubDocs/DEC/WSMD/lakes/docs/lp_2-strokereport.pdf

rslifkin said:

For this reason alone, if you want a tiny dinghy engine, I'd take the current Suzuki 2.5 over the Honda 2.3 any day. The Honda is air cooled, the Suzuki is water cooled and significantly quieter (plus slightly cheaper). Both weigh 29 lbs in the short shaft version.

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Yes, that's what I found - it's much quieter than the Honda. I solved the carb gumming problem by using the "TruFuel" they sell at Home Depot. It's like $20/gallon but worth it if you don't use the engine much, or use it for lots of short trips. That said, I had trouble with the Suzuki idle speed climbing for no reason, and the spin-around-for-reverse was not always ideal.

rslifkin said:

For this reason alone, if you want a tiny dinghy engine, I'd take the current Suzuki 2.5 over the Honda 2.3 any day. The Honda is air cooled, the Suzuki is water cooled and significantly quieter (plus slightly cheaper). Both weigh 29 lbs in the short shaft version.

Click to expand...

We did the research and decided a suzuki was the best choice for us too, because of it's quietness. The trouble is, we couldn't find a suzuki or any other small motor within a 200 mile radius! This was the summer of '20 when everybody was buying everything because they were staying home due to the covid scare. A local honda dealer knew of a customer who had mentioned he wanted to sell his honda 2 because he didn't use it so thats how we ended up with it. It was like new and has served us fine. Just a little noisy at higher RPM's but it's reliable and better than rowing, by far.

The Honda 2hp was the worst new piece of machinery I ever owned. Yes it started every time but , you will definitely go deaf in at least 1 ear. You will also lose all feeling in your throttle hand. Then when you lay it down on deck you will have a puddle of gas with just a touch of black exhaust .
I replaced it with a 2.5 Yamaha. That was much better.

FlyWright said:

I agree completely...but there's also the lower maintenance without an impeller. That also matters to some folks.

The Honda has an interesting centrifugal clutch that only turns the prop when throttle is applied. The ladies of my family loved driving with that feature years ago.

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That's the other difference. The Suzuki has a manual clutch, so it's easier to go very slow. But still no reverse.

interesting requirement. Most GB owners leave the OB attached to the dink and lift both on board with the topping lift (most have added an electric winch).

I will just toss this in here. Propane 5HP Mercury 65lb on my 270 RIB
Recommend it for ship to shore. Using 10lb propane tank

boomerang said:

I've never measured the fuel consumption of our honda 2 but I don't think it's more than a quart an hour! I carry an extra gallon but never had to use it.

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You're right...I wrote that in a hurry and meant 1 QT/hr at 5 mph. That's 20 MPG.

Flatswing said:

interesting requirement. Most GB owners leave the OB attached to the dink and lift both on board with the topping lift (most have added an electric winch).

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We have a 1000lb Jackson davit on the starboard side which lifted our old dink. It was the previous owner's 2014 9' 6" Zodiac with a 20hp Yamaha 4S and helm console, had to hang out over the aft cabin seat, the longer of the two back there. The lower unit was up close to the cabin wall. The lower unit and prop, and the aft end of the tubes, made sitting on that side difficult to impossible and my wife really likes to sit back there and fish with others.

Because the lower unit needed to overhang the cabin I couldn't put the bow very close to the main cabin. Last, even with the dinghy chocks holding it at an angle to starboard it was jammed against the flybridge stair rail and overhung the outboard handrail and then out a few inches into the walking space of the deck.

The PO had to have helm seating with an electric start. He also had to have a Yamaha 4 stroke. He told me that the 20 hp was where those started at the time. Because of the weight in the back, he had a canvas bag of weights in the bow to keep it down when moving. The 6 gallon gas tank, bag of weights, no storage compartment, and the helm steering, left little room for people and a dog.

Luckily the Zodiac seams opened up in a big way which forced me to do something so I sold it all. As you can see, this dinghy setup was just not for us.

Reading all of the above posts reminded me that outboards and I do not get along. At all. Ever. I had the carb on this one rebuilt three times in 3 years. Granted, this was mostly due to our limited use.

I think I will give the electric motors another look. As long as one will push the boat to 5mph or so in reasonable conditions I think it would work for us. At this point, we don't care about exploring far away nooks and crannies or going fast. If we do want to start doing so, or it doesn't work for some other reason then I will sell it and get something else!

firstbase said:

I am replacing our old dinghy with, I believe but not yet purchased, a new Highfield 290 CL RIB. Aluminum hull, Hypalon, 9'6", 126 lbs. DInghy use is ship to shore, no long excursions. I need to find a motor for it that I can take off the transom when we are done and store it either laying down in the dinghy or on some sort of bracket nearby. Day in day out use is for me, my wife, and a 70lb dog. Max load, on rare occasions would be 4 adults for a short trip to shore. Don't really care about being able to get up on a plane.

I have looked at the electric motors, E-Propulsion and Torqeedo, and they do look inviting for all the well-known reasons but....I don't know. I don't need to go fast but need to go 5 mph at least.

I think I am more sold on a small outboard, preferably with an internal gas tank, an oil/fuel containment system so I can lay it down, and light enough to be able to take on and off either in the water or on deck after lifting it up. Lifting 100lbs in my garage is one thing. Doing it in the back of a dinghy is another.

Does anyone here have a motor of this type? Any suggestions, thoughts?

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If you are close to me, I have a Honda 9.9 manual start outboard for sale. Has about 3 hours on it. It is difficult for me to start because my upper body strength has long since departed this earth and it is a bit too fast, for me, on my 15ft RIB.
You come get it. The price is $800 below retail

OldDan1943 said:

If you are close to me, I have a Honda 9.9 manual start outboard for sale. Has about 3 hours on it. It is difficult for me to start because my upper body strength has long since departed this earth and it is a bit too fast, for me, on my 15ft RIB.
You come get it. The price is $800 below retail

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Thanks, Dan, I appreciate the offer but at 90+ lbs it's just too much for what I need. I just can't see lifting that on and off the transom without ending up at a chiropractor's office.