What is The Biggest Outboard motor can I put on a 1977,14 foot Boston Whaler?

My boyfriend who works on boats all the time said a 115 yamaha would fit nice on it might be a little over overpowered as long as your hull is nice and sturdy and your transom is good you should be fine putting that on there.What is The Biggest Outboard motor can I put on a 1977,14 foot Boston Whaler?
It depends on many things.

1.) Check the "certification plate", likely on the transom. It should have a maximum recommended horsepower. If the plate is missing, look up a similar sized new Boston Whaler -- it will likely be similar.

2.) Check the transom. Most fiberglass boats usually have wood reinforcing under the fiberglass in the transom. I believe Boston Whalers are the built in this fashion -- maybe another reader can correct me if they are not. The problem -- humidity migrates into this wood all summer long, through the fiberglass and also through any holes drilled in the transom. Come cold weather, this humidity cannot breathe out fast enough and condensation occurs. Over time, the wood gets rot in it, and the transom loses strength. So, on an older boat, you often should not put a "maximum horsepower" motor on it.

3.) If the transom is in good shape, you can exceed the maximum horsepower rating for the boat if you know what you are doing. We have gone so far as to put a 115hp motor on a boat rated for a 75hp. Before doing this, check with your insurance company to make sure they will not decline coverage. As well, if you exceed the suggested rating by more than about 20%, consider mounting the motor slightly off-centre on the transom to counter-act the torque effect. Typically the trim tab on the motor handles this, but if you over-power the boat by a great deal the trim tab may not be enough.
The hp rating on the capacity plate is determined by a formula dictated by the Coast Guard. Width, length and other dimensions I cannot remember. They say what you can put on max for safety reasons. If you want to run faster do some research on how high you can raise your motor with out cavitation of the prop (air surrounding your prop higher prop speed higher engine speed no grip on water) then you have less drag of lower unit = more speed. Put a tach on your motor and know your rpm rating for it. Not enough pitch in your prop motor over reves to much and it bogs and you go slow. A lot of variables are involved but it is worth your while to do the research th wring the most out of what you have.What is The Biggest Outboard motor can I put on a 1977,14 foot Boston Whaler?
The builder put a plate on the hull stating clearly the power and load ratings of the boat. If the builder believed the hull could handle more power they will most definitely say so - it is a marketing tool. There may be very good structural reasons why larger engines should not be fitted to this boat.



There are lots of issues with over powering a boat. You may have no insurance. The authorities may take a very great dislike for your boat and the operator if the engine is over the boat manufacturer's rated power - very much so if an incident occurs too... Then, as mentioned, the hull may easily cope with over powering when in new condition, but over time rot and stress can dramatically reduce the hull's ability to survive the extra loads.



There is your own ability to consider, there is a substantial skill level in operating a fast boat at speed, and understanding how the trim of a high speed boat affects it. It takes years to learn how to control a very fast boat with the minimum of risk, and mistakes at speed can be serious - or fatal. Getting a boat to speeds well above the designer's brief means you are in a totally unpredictable zone, all sorts of funny things could happen.



If the boat is not fast enough with the rated maximum power then upgrade - it will be far safer and probably cheaper in the end.



In my experience it is sometimes too easy to get carried away with a boat due to emotional or other attachment, but if it really isn't suitable for what you are trying to do with it then you have to consider getting a boat that does.



And speed ALWAYS costs.
Listen to John D, but I'd also caution you. Exceeding the hull speed and/or overloading the back of the boat with weight will completely ruin the stability profile that the boat was designed with. The end result is that you can swamp the boat by decelerating, flip the boat by driving into a headwind, or simply rolling over if you take a wake or a swell on the beam. There's no legal protection for you if you claim that you didn't know better. BE careful!What is The Biggest Outboard motor can I put on a 1977,14 foot Boston Whaler?
I don't know of a 14' Whaler; the max rating on a 13' is 40HP, 15' max is 70HP. Your boat will be less controllable and waste more gas and probably not go a lot faster by overpowering it. If it's a 13', 50HP should be OK, 115 would be ridiculous. You will run your motor at such low RPMs that the prop will be less efficient and the engine will get carbon buildup.
i would think a 50 hp should be the most but check the capacity rating one the plate on the boat
I know someone with a 14' boat and he has a 150 merc on it. Maybe you can a little higher who knows.