Max HP /Transom...answer me this...

[RobDar]

So the Max HP rating....
In speaking with one company rep whose company lists max HP in pounds...not in actual HP...I was told that this is because the max HP listed by boat companies is actually a motor weight limitation, not so much a HP rating...and with the increase in the use of four strokes, which are heavier...you get the picture

...but then when you go to other companies sights they list both four strokes and two strokes of the max HP rating as motor options...

so what is the deal? Is the max HP predicated on the transom and general boat construction or is it based on the weight of the motor?

 

[bassboy1]

Re: Max HP /Transom...answer me this...

It is all general. The rating is actually nowhere near what the boat could hold. So manufactures will weigh one motor or the other and use that as a max sticker rating. But, if they put a heavier motor on, but it meets HP sticker rating, what gives? The boat can hold a lot more engine than the sticker. Nothing is really exact. That is why all stickers are in 5 or 10 horse increments. Its all rounded. Otherwise, a boat rated for 75 may be actually able to hold a 92.435 hp. Just stay within the number to remain legal, and don't really worry bout anything else.

 

[JB]

Re: Max HP /Transom...answer me this...

That's a good question, Rob. I am sure a lot of people are wondering.

One example is the classic (1973-1999) Boston Whaler Montauk 17, which was rated for 100HP. We know that carbed 2 stroke 100s weigh right around 300-320LB. After the rating system for HP in outboards was changed in the mid 80s the OMC 100s became 90s, but the boat was still rated for 100.

The problem came up when the EFI 4 strokes started showing up. The Yamaha and Suzuki 90s weigh over 400lb, with Honda and Merc close. Many of us, self included, put Suzuki DF70s (about 350lb) on our classic Montauks and were happy. Folks who put the big 90s and 115s (!!) were not always so happy unless their lust for thrust outweighed their desire for a nimble and stable boat.

Boston Whaler dealt with that by rating the transom of the classic Montauk and its 17' sisters at 400lb, but not changing the HP rating. That means that some engines that meet the HP rating are judged too heavy for that hull.

I guess the bottom line is that we need to ask the makers for a transom weight rating as well as a HP rating.

Too many folks give up handling and stability by over powering their boats already. Now we have to worry about overloading the transom, too.

 

[RobDar]

Re: Max HP /Transom...answer me this...

so somewhere along the line someone has figured out how the boat will perform best regardless of weight or HP...it could be either limitation.

 

[dingbat]

Re: Max HP /Transom...answer me this...

so somewhere along the line someone has figured out how the boat will perform best regardless of weight or HP...it could be either limitation.

It's may not be performance limitations as much as physical limitations.

This issue comes up all the time with boats that have self bailing decks. The additional weight on the transom can force the scuppers under water on some boats allowing water to come back in thru the drains. It?s not good to have your drains below the water line.