Upping engine size...re-rating??

[MASTERBrian]

I have an 18' Bass Buggy Pontoon. It currently has a 50HP Johnson 2stroke on the back. It's rated for a 60HP.

The part of the transom the motor is hung on is currently wood about 1-1/2" thick. That is riveted/bolted to the rest of the aluminum transom bracket. The wood is starting to show it's age and I believe for around $100-150, I can get a piece of 1-1/2" thick aluminum to hang the motor onto. Since I'm sure the aluminum would be stronger, I can't see any issue with that. I've thought about the ply again, but figure I'll spend $50+ just for the ply and honestly, the aluminum is almost easier for me to get and it'd never be an issue again!

My question, is would this allow for a little larger motor to be placed on the boat? I'm thinking a 75HP might be nice. The 50HP is a bit of a dog on this boat. I top out about 12mph. 15-20 would be nice!

Before this turns into another one of those threads where everyone talks about liability, insurance, etc....I realize all of that and wouldn't do, UNLESS there was a way to get the boat re-certified for a larger motor, so it would be 100% safe, legal, insurable, etc.. I just didn't know if anyone does that or if it would be an absolute nightmare, both time and money wise!

I'm not looking for something that is dangerous, etc., I've just thought if I could come up with a 60hp motor I'd look at doing the swap and since I'm most likely beefing up the transom with aluminum, instead of plywood, could I go a size bigger and get it re-certified for that. Maybe no one does that!!

 

[Scott Danforth]

transom material has nothing to do with HP capacity tag. no way you could get the boat capacity changed without making the boat longer, adding another toon log, or adding larger diameter toon logs. Hp for pontoons = volume of pontoons (cubic ft) x longest pontoon length (ft) / pontoon diameter (inches) then round down to nearest 5hp increment.

also, since your pontoon is a displacement hull, even going to 90hp wont help until you add lifting strakes and get the boat to plane (many posts on here about going slower with more hp on pontoons)

 

[Woodonglass]

It's not a question of beefing up the portion of the transom that the motor attaches to. Its the brackets and the welds to the main superstructure of the boat that the rating is for. The 1 1/2" thickness is to accomodate the motor bracket and has little to do with the HP rating of the boat especially on a pontoon. I seriously doubt you'll get a new rating unless you do some modifications to the entire motor mount and reinforce it with additional bracing and welding. Not sure if there is a way to get it re-certified for a Larger motor. Might have to contact the State Dept of Motor Vehicles Boating Division and see what they say.

As always PICS of your boat would greatly assist us with helping you.

 

[GT1000000]

I now and completely understand the never ending quest for more power...I am a gearhead...
My question is this...
Why are you not satisfied with the 50 horse motor?
Are you wanting to go faster?
Pull skiers or tubers?
Were you happy with the amount of power before and recently it feels sluggish?
Remember the price for more power is an increase in fuel consumption...
If you are looking to re-power, modern engines have a horsepower rating at the prop instead of older engines which were rated at the crank...what year is your engine?
You could add a lifting pontoon to the center of the toon and make a large increase in power without having to spend more money on a new engine...here is a link to what I am talking about...
http://www.pontoonwaterglide.com/index.asp
As has been mentioned, more horse power does not always increase boat speed...
Have you considered re-propping?
Just changing/replacing the transom will not automatically allow you to increase the power rating of your toon...