I have a 1977 Starcraft 16 foot long, 5 foot 2 inch beam "V"-shaped aluminum utility and am thinking of purchasing a 25 hp tiller-controlled Yamaha for it.
My question is whether the 175 pound Yamaha will be too heavy for the boat, especially if operated alone with no human ballast to move forward, and if so what I can do about fixing any resultant trim issues.
The boat is in very good condition overall and in excellent structural condition. I am increasing height of transom with marine ply and 1/4" thick aluminum plate (see photos). I am sure that transom will be strong enough for 25hp, my question concerns the weight of the 25 hp Yamaha.
The boat weighs 350 lbs empty hull and I weigh 175lbs.
I have tried my long shaft Yamaha 9.9 -- weighs 90 lbs -- on this boat with only me in it. Once on a plane, the trim is fine with no porpoising but the hole shot has the bow up in the air even when trimmed all the way in. The 9.9 pushes the boat to about 20 mph in relatively smooth water.
Part of the issue is that the transom is relatively narrow at 4' 8" as compared with today's boats which are somewhat wider. Further, this is an empty hull with no decking to offset the weight of the outboard.
I'm thinking that perhaps increasing the negative trim with wedges (bringing the bottom of the outboard closer to the transom to create more stern lift) and some ballast in the bow (say, around 70 - 80 pounds) when operating the boat alone may substantially mitigate the unfavorable effects of the heavy outboard? Maybe even some static trim tabs to help counter the lifting of the bow during hard acceleration (would like to avoid this option)?
I'm gonna put 100 pounds or so of ballast in the stern and see how boat sits and runs with the 9.9 and experiment with counter-acting bow ballast to get a feel as to whether this may be doable.
Any opinions / suggestions in the meantime?
My question is whether the 175 pound Yamaha will be too heavy for the boat, especially if operated alone with no human ballast to move forward, and if so what I can do about fixing any resultant trim issues.
The boat is in very good condition overall and in excellent structural condition. I am increasing height of transom with marine ply and 1/4" thick aluminum plate (see photos). I am sure that transom will be strong enough for 25hp, my question concerns the weight of the 25 hp Yamaha.
The boat weighs 350 lbs empty hull and I weigh 175lbs.
I have tried my long shaft Yamaha 9.9 -- weighs 90 lbs -- on this boat with only me in it. Once on a plane, the trim is fine with no porpoising but the hole shot has the bow up in the air even when trimmed all the way in. The 9.9 pushes the boat to about 20 mph in relatively smooth water.
Part of the issue is that the transom is relatively narrow at 4' 8" as compared with today's boats which are somewhat wider. Further, this is an empty hull with no decking to offset the weight of the outboard.
I'm thinking that perhaps increasing the negative trim with wedges (bringing the bottom of the outboard closer to the transom to create more stern lift) and some ballast in the bow (say, around 70 - 80 pounds) when operating the boat alone may substantially mitigate the unfavorable effects of the heavy outboard? Maybe even some static trim tabs to help counter the lifting of the bow during hard acceleration (would like to avoid this option)?
I'm gonna put 100 pounds or so of ballast in the stern and see how boat sits and runs with the 9.9 and experiment with counter-acting bow ballast to get a feel as to whether this may be doable.
Any opinions / suggestions in the meantime?