hi guys,

a couple of weeks ago i posted a question about outfitting a 14 foot md-v lowe with a merc 25/20 jet and got a ton of great feedback. that said, i've got another question.

as you might remember, i live in wisconsin and can't get much help here... i can, however, seem to get planty of beer, cheese and large women.

all joking aside. here's the deal:

ive' recently been offered a new yamaha 40 hp. jet for a really great price. knowing yamaha's reputation, it's pretty attactive, BUT 40 hp is far too much for a 14-foot boat.

does the 40 hp. rating mean it's really like a 28 at the pump, and if so, is this still too much for my boat which is only rated for 20 hp.?

(FYI, i've called lowe and they stick to the "if it's rated for 20 hp, that's what it should have on it," but i always overpower prop driven boats and see no reason a jet couldn't do the same.)

weight differences are 128 lb.s for the merc 25/20 and 203 lbs for the yamaha jet. does that totally affect things? i would like to row the baot, but don't expect drift boat-type performance.

thanks for the help guys, your advice has proved invaluable.

-jason

I had 14' lund rated for a 25hp and it did fine with that much power. I now have a 15' smokercraft rated for 40hp, I have a 25 yamaha on it and it does great. I wouldn't put a 40 on your Lowe but personally think a 25 would be fine. My thoughts on the 40 are how heavy it is and how it would affect the handling more than the 28hp you figure you'll get with a jet.

P.S., both my 25hp yamahas were props.

i got a 40 jet yamaha .28 horse at the pump. on a 16FT flat bottom boat it's rated for 25 horse.try putting 200 pounds on the back of your boat and you .and see how it will sit in the water .my boat rids good with 2 pepole are 1 but 3it slowes down to much.

XS,
I don't have as much experience as the other guys on this site, but have been hitting it pretty hard in terms of research on this topic. The common theme I've heard from people on this site and other places is "don't underpower". In your case I'm assuming you're looking at the Yamaha 40, 4-stroke jet. It's my understanding that this motor produces approximately 28 hp at the pump. Nothing against 4-strokes, but for a jet pump I've heard a 2-stroke is preferable because it winds up/produces power more quickly than a 4-stroke which translates to better hole-shot. Your boat sounds like it is fairly light so don't know if this will matter as much. If I were you, I'd be more concerned about the weight issue. How well does your boat ride with you and a 200 lb motor in the back? One other thing to consider is the height of your transom. You will probably have to increase it's height to somewhere around 27" via an engine jack or transom extention.

When I did my research I spoke with the folks at Wooldridge who have forgotten more about this topic than I will ever know. They in turn gave me the number for the folks at Specialty Manufacturing (the guys who make the outboard jet units). Specialty has a brochure that helps with selecting the right size engine for a boat based on weight. Between Wooldridge and Specialty Manufacturing I got almost all my questions answered.

I don't have Wooldridge's number, but they are on the web. Shoot me an email if you want to discuss further (jsullivan@kennedyusa.com)

JMS

XS -

Welcome back.

You are looking at the EXACT combo I had. I had a 14' Crestliner jon boat with a Merc 20 prop, pulled it off and put a Mariner 40 hp motor, 28 hp at the jet, on it. Same powerhead as the Yama if you are looking at the 2 stroke. It weighed about 200 lbs. Definitely sat down a bit more than the Merc 20, but I ran it on alot of the rivers out here, including the mighty Columbia many times and it was great. The added power was welcome many times when I would be in flat, moving water. Never had a problem with the setup and now my friend has it. If I was doing it again, I would do the same setup.

I did have a riser bracket welded so I could raise the motor up about 4' so the shoe would sit correctly with the bottom.

Good luck.

XS, Just have to add my 2 cents. I used a Merc
45 w/pump on my 16 Alumacraft. It was great, but with me back at the stern also, it sat too deep when not under way. Had waves come in over the stern in rough water. If I didn't eat so much or had been born to smaller sized parents this my not have been a problem. What did happen that was bad news however, is the transom began to push out or bulge. I bolted on a .19 inch thick aluminum plate and that stopped that. I don't know if it was too much trailering or too much power that caused the problem. If you plan on moving up in power, and hence bringing the motor weight to 200 lbs., I'd add a 40inch by 12+inch
plate on the back just to make sure you don't have the same problem.