Yamaha F70 or T60?

[GregF]

The Zeke 70 is 81 pounds heavier than my Yamaha. I looked at it

[ROLAND]

The F70 breathes better because they have 4 valves per cylinder.

I am still not convinced the extra 5 HP is worth the extra 100 pounds, going for the F75. If you do that get the 90 Yam or 115 Merc.

Greg.. question for you ( or anyone else who wants to chime in ).. as stated in my previous post I have the F75 on the back of my 20 foot toon.... when I was buying the boat, it came with a 50 hp yam 4 stroke.... the boat was rated up to a 75, so I went with the upgrade. The F75 weighs 369 lbs.... I believe the yamaha F90 also weighs 369 lbs... if both motors weigh the same, then why couldn't I have put a 90 on the back end? Are there other factors other than just the weight of the motor?

[GregF]

That is the classic question that has been beat to death here and on THT. When they specify a motor size, is that really based on weight or horsepower. Since it is really just a guideline unless your state has codified it into law, I think I would make my decision based on weight.
In Florida the owner can scrape that sticker off. The USCG doesn't require it at all on a boat over 20' or a boat with multiple hulls.

[rancherlee]

There is a mathmatical formula for figuring out HP ratings for a pontoon that's based on the displacement flotation, length, and diameter of the tubes. Maximum allowable HP rating = total cubic feet floatation x length of longest tube / average diameter of tubes. You are allowed the round up to the nearest 5hp increment. I've run that calculation won several pontoons and it comes out almost dead on in every case. My pontoon was under rated quite a bit but after researching I found out that they had offered a Heavy Duty transom pod option that carried a 75hp rating and that my standard transom was only rated for 50hp/250# hence the 50hp on the now missing capacity plate. Adding the 3rd tube I'm now good for 115hp (113hp calculated and rounded to 115)