How much hp do I need ????

[Gigawatt man]

This is my first time on this site, so I hope I'm posting in the right place !!! I recently purchased an older Aluminum 21 foot Sylvan. It came without motor and I'm trying to figure out how much hp I'll need to make it perform okay. It'll likely never be used for anything except fishing and probably never carry more than 4 adults. Would a 90 hp fuel injected Nissan be enough? I would appreciate advice from anyone with experience on this topic. Thank you.

 

[roscoe]

Re: How much hp do I need ????

What is the boat rated for?<br />This is a deep-v hull, correct?<br />In my opinion, 90 should be good.<br />Try to get 80% or more, of whatever the boat is rated for.

 

[Solittle]

Re: How much hp do I need ????

I would go for the largest 4 cylinder outboard that is allowed for your boat - that would be in the 100-135 hp range. A 90 with a full load of people & gear seems a tad light to me.

 

[dyac156]

Re: How much hp do I need ????

I just bought a 14 foot Jon Boat for river fishing and it does not have a rating plate. The title is from NJ, it sayst it is a 1978 Sea. Can anyone point me in the right direction?

 

[Gigawatt man]

Re: How much hp do I need ????

Hello Roscoe, thanks for the reply. The boat is rated for 180 hp and I have ridden in one exactly like it, that had a 150hp Merc. We had four large people and the live well had about 35 gal. of water and the fuel tank was full with 45 gal. My GPS said it was doing 42 mph. I don't need to do 42, if I can get 30 mph, I'll be happy.

 

[roscoe]

Re: How much hp do I need ????

Sorry, I guess I haven't seen any Sylvans that were rated that high. It must be bigger and heavier that what I was imagining. <br /><br />So, a 90 may be too small.<br />Hopefully someone else will chime in here.

 

[JB]

Re: How much hp do I need ????

I agree with Roscoe's advice, Digger. Most boats perform well with 70-80% of rated max HP.<br /><br />By that guideline, I wouldn't put less than 130HP on her, and think a 150 would be ideal.<br /><br />Good luck.

 

[sloopy]

Re: How much hp do I need ????

Try your best to get as close to 180 as possible. If you get a 90 horsepower engine it will be at full throttle to get you to 30 miles per hour, at full throttle it will use more fuel and run the engine down faster than if you had a 180. with the 180 your cruise will be over 30 and using less fuel. It will also be easy-er on the engine.

 

[walleyehed]

Re: How much hp do I need ????

Trust what these boys are tellin' ya. I've got a 18ft D.V. starcraft rated for 150, and I've got a 115 on it.....should have went with at least a 130. 4 people, livewells full, 26gal fuel, 16 tackle boxes, 47 rods......you get the picture.

 

[Jack Shellac]

Re: How much hp do I need ????

You will be a lot happier with more power than you need than with too little. I'd also recommend a 150 for this boat. You don't have to open it up, but there may be times when you're glad you've got the extra horses.