Upgrade motor.

NewtBootGoofin · Feb 4, 2024

As the photo shows, my 14ft semi vhull tinny has a 1983 7.5hp Evinrude on it. Motor runs great. I get around 13mph max out of it with myself (300lbs) and all of my mods and gear on the boat. I played around with weight distribution and feel I’ve got it about as good as it’s going to get. I have a coworker that wants to sell me an older (he’s not sure of the year) 9.9 Johnson. I’ve read that the 9.9’s can be upgraded to 15hp with a carburetor swap. Do y’all think that would do well to get me along a little better? Would it plane out my craft? I live on the Harris Chain Of Lakes and would love to be able to plane out and get around the lakes efficiently in my little boat!

Crazyboat · Feb 4, 2024

1st question is, what is the boat rated for? The extra ponies makes a big difference. I speak from personal experience. I had a 7.5 rated Sear 12' boat w/7.5 HP on back as a kid, I went and bought a 15 because I'm crazy and stupid @ 15 years old. Tore the bow of the boat up something awful over the next 2 years. Also it should be noted that some engines can be made into a 15 with a carb swap, others need additional modifications too.

NewtBootGoofin · Feb 4, 2024

I’ve had quite a hard time finding any info about this hull. The capacity plate is missing as well. I ran a HIN check on it but pulled back very little info. All I know is that it is a StarCraft Marine manufactured in 1973. Through hours of research on the web, I’ve found that it is most likely a “Sea Scamp” model. Of all of the images of I’ve searched through, that is what it looks the most like. And through further research I’ve found that Sea Scamps were rated for 15hp max. Though, I’m really not sure.

airshot · Feb 4, 2024

A 14' Starcraft is a well built boat, even their economy models. I would be comfortable with a 15 hp if the boat hull is in good shape. I had a 1994 Starcraft 14' but rhe bigger model with a 35 hp rating. Had a '94 9.9 with carb upgrade to 15 hp. Worked great, about 22-23 mph by myself at 160lbs. Would plane with two at 18-19 mph. Do check thoroughly to make sure that particular 9.9 can be upgraded with just a carb. Some can but a few can't be....good luck

NewtBootGoofin · Feb 4, 2024

Just did some further research and I was able to find the dimensions of a 1973 Sea Scamp on another forum. I went out to the garage and measured mine and this is indeed a 1973 Sea Scamp! I’m just excited that I finally know what my tinny is! Lol

NewtBootGoofin · Feb 4, 2024

airshot said:
A 14' Starcraft is a well built boat, even their economy models. I would be comfortable with a 15 hp if the boat hull is in good shape. I had a 1994 Starcraft 14' but rhe bigger model with a 35 hp rating. Had a '94 9.9 with carb upgrade to 15 hp. Worked great, about 22-23 mph by myself at 160lbs. Would plane with two at 18-19 mph. Do check thoroughly to make sure that particular 9.9 can be upgraded with just a carb. Some can but a few can't be....good luck

Great info! I would love to be able to get 20mph out of her. 13mph gets me around but at 20 I would feel like I’m really moving.

LaqueRatt · Feb 5, 2024

I've been playing around with motors on 14' tinnies. I found a 14 HP works pretty well and gets up on plane without a lot of trouble. An 18 is much better and IMO a 25 is almost too much. My current Mirro is rated for 35 BTW. I doubt if it's worth your time and money to mess with a 9.9. Everybody wants to turn a 9.9 into a 15 so naturally the parts are expensive and hard to find. It's almost cheaper to just buy the 15 you want, even if you just need the carb.