Motor size question

[reelfishin]

I have a 19' Renken 900 V hull that I bought sans motor, I was wandering if a 70HP Evinrude that I have would work on it? The hull is rated for 150HP, but had an 85HP Johnson on it before I got it. The 70HP is a fresh overhaul and runs strong. I've been looking around for an affordable, larger motor with no luck and was thinking of using the 70 that I have here.
I am not concerned about speed, but I don't want to hurt the 70hp motor and it does need to get on plane. The boat weights about 1500 dry without motor and will carry 3 people (700lbs), and has a 40 gallon fuel tank and a 20 gallon livewell.

 

[hitace]

Re: Motor size question

70 hp is a little on the light side for a 1500 pound boat but it being a evinrude 70 it should get you on plane.but it seems like this is going to be one of those times where your ether at full throttal or you aint moving

 

[Solittle]

Re: Motor size question

The 70 will probably get you up on a plane but it will be workin hard to do it and I would guess you will need to run it flat out all the time. A 115 would be a better choice on the low end.

 

[tashasdaddy]

Re: Motor size question

you may have to adjust prop pitch, to keep the rpms up, to keep from lugging the engine. kinda like a pontoon.

 

[Texasmark]

Re: Motor size question

You set the stage.......don't care about speed. No doubt in my mind that a 70 will plane your boat. If you don't believe that, go to the old-omc web site and look at the cruisers that 40 hp and fat 50 engines planed out and that's when they were rated (Brake) hp......at the powerhead, not prop rated as I'm sure your 70 is rated.

Buttttttttttt those were light boats for their size and most had flat planing surfaces for most of the boat's length......hard to get too stylish with flat sheets of marine plywood.....course that's before they added all the beautiful babes in swim suits to get your and my attention. Grin.

If you need help add a whale's tale or smart tabs. With those accessories you can probably plane at 15 mph.

Also, no doubt that the engine will be running flat out most of the time and you won't be able to enjoy the fuel efficiency that you would get with more HP; but that depends on a lot of things, load, wind, waves, #of bathing suit babes aboard and all. (The beer cooler is not empty yet)

But, gotta weigh the cost of another engine vs these other things.

Looks like you can make this a winner.

Mark

 

[Frank Acampora]

Re: Motor size question

I had an 18 foot Renken. With a 75 Chrysler on it it did 32 MPH. Your 70 Rude will probably be ok on the 19. Those 3 cylinder 70s are sweet little engines--well designed. You may just need to play around with props. I think my 18 was rated for a 140. It originally had a Chrysler 140 and did 42 MPH.

And for a low end boat --I'll get to that in a moment-- It may surprise you. Mine had good manners in rough water. Of course, in big waves you will get a pounding in any boat, but mine never gave a scary ride. I was happy with it. I only sold it because I wanted a 20 foot cuddy.

Now, to the low end boat: The two halves of the boat are put together with pop rivets and the factory did not use back-up washers. So: in rough conditions with constant pounding on the hull, the rivets can pull through the fiberglass. Mine did--from the bow all the way to the middle of the hull. You may want to remove the rubber rub rail insert, drill out the rivets one at a time, and through bolt the hull together with someone on the inside to hold the nuts. I used 1/4 inch truss head SS swimming pool screws 1 1/4 inch long.