# Tohatsu 3.5 or 4 HP?



## galernikus (Oct 25, 2008)

Hello,
I have 8 foot dinghy and I need a outboard for it. I am thinking of Tohatsu 3.5 or 4 HP versions. 3.5 HP is over 10 pounds lighter, so I am wandering if that extra .5 HP is worth it? Any suggestions? Thanks.


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## bubb2 (Nov 9, 2002)

I would give consideration to the 4 horse. It has forward, neutral and reverse and can be connected to external tank.


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## sailingdog (Mar 19, 2006)

If weight is an issue, get the 3.5 HP. The external fuel tank connection can be done on the 3.5 HP using a simple modification to a spare gas tank lid...


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## josrulz (Oct 15, 2006)

I'm toying with that same question myself. We have a 10' Avon with the inflatable V-bottom, but we perfer a lightweight motor too. Not sure if your dinghy is inflatable or what it's rated for--ours is 10HP max.

All that said, we're thinking about the 6HP Tohatsu (or similar). The reason is that it's the same weight as the 4HP and 5HP models, and only 14lbs heavier than the 3.5HP, but with the extended range of external gas tank and more power to push through a chop.

I don't know if we'll actually GET a 6HP--we might end up with something used or new on sale. However, our thinking _right now_ is that it might be worth going from 41 lbs to 55 lbs but almost double the power. Just my two cents for now, and of course I might change my mind!


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## sailingdog (Mar 19, 2006)

There's a big difference when lifting the dinghy motor and trying to get it mounted on the dinghy between the 3.5 HP and the 4 HP. My friend borrowed my 3.5 HP Tohatsu last summer for a couple of weeks, because his 5 HP was in the shop. He ended up selling the 5 HP because of his wife. She was able to put the 3.5 HP in place without trouble...and preferred it to the 5 HP because of that. So does he.... since he used to have to do it all the time...now she can put the motor on the dink and put it away when they get back—or more importantly, when their two kids want to use the dink...


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## Brezzin (Dec 4, 2006)

3.5 hp is 41 pounds. the 4hp is 57 pounds. (per defender Website) That's pretty heavy to be muscling around. I don't even like the 41 lbs of the 3.5 but that's me. you need to pick the outboard based on how you plan to use it. For instance, I have a Honda 2hp at 27 pounds. I keep the motor on the dingy as it hangs from my davits. I use it primarily for just trips between shore and the boat and it meets those needs. So weight is an important factor for me where as if I was to use the dink for long trips, Horsepower would be more important.


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## josrulz (Oct 15, 2006)

All good points, and we may end up with the 3.5 too for the reason of weight. But it's good to note that the 4HP is the same CC as the 5HP and 6HP (the weight of the 5 and 6 is actually a couple pounds less because no internal tank). So you might as well get a 6HP if you're going to the 4HP weight and your boat can accomodate it. Of course it costs more, so that's easy to say.

I like that Honda 27 lb weight too. We lifted one up at the Boat Show and it really is light! But I worry it's too small to push a 10' inflatable in a chop.


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## painkiller (Dec 20, 2006)

josrulz said:


> I'm toying with that same question myself. We have a 10' Avon with the inflatable V-bottom, but we perfer a lightweight motor too. Not sure if your dinghy is inflatable or what it's rated for--ours is 10HP max.
> 
> All that said, we're thinking about the 6HP Tohatsu (or similar). The reason is that it's the same weight as the 4HP and 5HP models, and only 14lbs heavier than the 3.5HP, but with the extended range of external gas tank and more power to push through a chop.
> 
> I don't know if we'll actually GET a 6HP--we might end up with something used or new on sale. However, our thinking _right now_ is that it might be worth going from 41 lbs to 55 lbs but almost double the power. Just my two cents for now, and of course I might change my mind!


I have the 6HP Tohatsu for a 10'4" Achilles air floor. With one adult and a pair of kids, the 6HP will get the Achilles up on plane. With two adults, no planing. Getting the OB on and off the mother ship is interesting but do-able for one person. I always end up with a little bit of grease on my shoulder after doing it. The inflatable will take up to a 10HP, but there's no way I'd lug that sucker around except by car. If you don't have any need to entertain the kids by zipping around the harbor, then smaller might be the way to go.


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## josrulz (Oct 15, 2006)

painkiller said:


> I have the 6HP Tohatsu for a 10'4" Achilles air floor. With one adult and a pair of kids, the 6HP will get the Achilles up on plane. With two adults, no planing. Getting the OB on and off the mother ship is interesting but do-able for one person. I always end up with a little bit of grease on my shoulder after doing it. The inflatable will take up to a 10HP, but there's no way I'd lug that sucker around except by car. If you don't have any need to entertain the kids by zipping around the harbor, then smaller might be the way to go.


Yeah, the weight of the 3.5 is appealing, and no, we don't need to entertain. But we will almost always have at least two adults in the dinghy and sometimes three. So we just want to make sure that if we do want to go explore a little further away that we'll have range and also the power to cut through a chop and into the wind if needed to get back to the boat.

I say all this without any personal experience on modern outboards. I'm still trying to figure out what the "sweet spot" is that will meet our needs.


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## TohatsuGuru (Oct 3, 2007)

One option to consider. You can get the 4 and if you decide it just wasn't enough power....You turn it into a 6 by putting the 6 hp carburetor on it.


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## lans0012 (Jul 16, 2008)

*Find a two stroke*

Hey OP I just replaced my nissan 3.5 2 stroke with a new 6hp for my sailboat the difference is huge for the boat because I also went from a 20" to 25" shaft and now have forward and reverse. But, the 3.5 is 30lbs and my 6 is 60ish. There is no way that I would want to try and mount that on a dinghy unless I was going to leave it on for a long time. Try and find a 2000-2005 2 stroke Tohatsu, Nissan, Mercury as they are the same and 15lbs lighter than the new 4 strokes. Also you will save money.

30lbs isn't a huge diff in the big scheme of things but it does tie up your other hand when carrying/mounting. .02


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## tweitz (Apr 5, 2007)

I have the 3.5 for my dinghy, and while it is light, reliable and starts easily, it certainly not overpowered. My biggest downside is that it has a miniscule fuel tank, and cannot be connected to an external tank. The result is that I have to refill it far more often than I would like, and often while bouncing around in somewhat tricky conditions. As much as the other characteristics of the engine are good, the tiny fuel would make me think long and hard if I had to make the decision again.


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## sailingdog (Mar 19, 2006)

Tweitz-

There's a mod for the 3.5 HP where you can use a modified fuel cap to attach an external fuel tank. You do have to pump fuel from the external tank to the internal about once an hour or so...but it is supposed to work pretty well.


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## donradclife (May 19, 2007)

I just bought another Tohatsu 3.5 2 stroke, which is strong enough to plane one person a 10.5 ft RIB, but weighs less than 30 pounds. The old one was still running after 14 years, but got caught under a fixed dock in Tobago with some high surf and the steering arm broke off.

The lighter motors also help when you have to lift the dinghy onto a rocky beach, or even pull it up a sandy one.


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## MoonSailer (Jun 1, 2007)

Where can you get that modified fuel cap to fill the internal tank????


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## sailingdog (Mar 19, 2006)

You have to make it yourself, AFAIK, no one is selling them commercially. There's a website that details how to make it on one of the WW Potter sites. I'll see if I can find the bookmark and post it here if I do.


MoonSailer said:


> Where can you get that modified fuel cap to fill the internal tank????


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