Too much motor?

[55'Fleetwin7.5]

I own an old 1953 Aero Craft 14' Aluminum boat. The transom has a 3' wooden piece (almost like a 2x4 but not as thick) horizintally on the inside and a trapezoidal piece of marine ply on the outside. I am wondering if I can use a 1958 18 hp Fastwin on it. I have two 1955 7.5 Fleetwin's but I am thinking on is too little and one maybe too much... Any thoughts?

Thanks

 

[External Combustion]

Re: Too much motor?

Your Aero is much the same as my Appleby. My 7.5 Scott Atwater has been enough to take me on two 1800 mile trips as well as countless miles just gunking around.

You are right, the two Fleetwins will be too much. Weight definately, and the horse might get exciting in a wind. Planing will not be an option with you and a buddy plus gear, but by yourself and a light tackle box the 7.5 will get you some surprising speed. You won't have to be strapped down, mind you!

 

[WTL]

Re: Too much motor?

About the best way I can answer that is my father has a 60s model 13'6" Sears boat with a 25 Mariner on it and has had no problems.

Meanwhile, I have a 14' Starcraft with a Johnson 28 on it and I am have some issues with it flexing.

The point of that is that there are going to be differences from boat to boat, but a lot of people have succesfully put much larger motors on smaller boats than yours.

Go ahead and slap the 18 on it and just check everything the first few times out to see that you arent having any problems. The transom wood has to be solid of course, and flexing is dangerous - but even if you have a problem, such I have had, istead of getting a new motor its probably just easier to shore up the transom or put some sort of extra support in the boat, which is what I am currently doing. Off hand I will say that 18 doesnt sound too big at all for your boat, but thats just gut instinct.

 

[55'Fleetwin7.5]

Re: Too much motor?

Where is the flexing? is it the transom itself? The current wood needs replacing and I can "beef" it up as you say... What should I be watching for in the flexing category?

 

[WTL]

Re: Too much motor?

My boat is flexing when I throttle up about 4 feet up from the transom in the floor, but I have taken out the bench seats which added some structrual support. I'm going to be riviting in cross bars of steel or something to add rigitity to the hull. That is a serious problem and I don't really expect that you will see that with your boat, but its something to keep in mind. You can also have flexing in the transom, and that will degrade the metal and cause it to crack or break in places you don't want it cracking or breaking.

If the transom wood is questionable, go ahead and beef it up. I really think that will be enough for you. Again, an old 18 horse really isnt that big anyways for that boat. Its 18 at the flywheel too, which means it would be a 15 or something by todays standards. They rate horsepower differently now.