Re: Slow pontoon boat 50hp merc, installed a 90hp merc, no change in gps speed
Something to think about...
Speed is a function of RPM, not horse power. More horse power will increase accelleration, not speed. Too much hp will cause more slippage, thus lower speed. The trick is to maximize rpm and reduce slippage. I have an 18' party barge with a 75hp 4 stroke Merc. I'm using a 14" diameter, 12 pitch with cupped blades. This is prop #4. The best I can get is 24.6 mph. My neighbor's 19' with a 90 hp 4 stroke Merc running a 13 pitch prop makes 22 mph.
Good Luck!
OS, yes my first pontoon, although my friend has a 21' pb with a 90hp and his numbers are about the same as mine, a bit better because his is a signature and a lot lighter than my overstuffed regency 22 pb with 26" toons. Between the extra weight and the extra drag from the toons, I go a bit slower. He also uses a 14x15p. Mine is rated for 14 people and I cannot remb the weight allowed. Thus the extra weight. I came from a 17' runabout maxing at 37mph, so this is quite a transition for me. We bought a joint at lake ozark in mo, and there are some *'n big a** boats on there and they don't care if they run you over. After the 3rd time I got air, I said no more and went looking for a pontoon and caught this one from a guy who had to sell it to save his home and homestead. I paid 1/3 of what he paid for it new, 3 years used, and it was well below kelly blue book. Had I bought new I would have prob bought a simpler model. The larger toons and boat allows me to manage the 4' wakes that attack the boat from the idiots in their cabin cruisers and off shore racing boats. Ignorance does not stop at the end of the highway.
I would be happy w 24mph and hope that the prop change will make a diff. I need a backup prop anyway, so it will be a good place to start. The jack plate is just too much $$$ right now for my retired income plus the cables will prob need to be replaced because they are just perfect now with no room from stretching. Its really not so much the speed, as much as the gas use, we were over $5 a gallon this year and that's too much for this 67 year old.
I do believe the acplate is too low in the water at 10.5" and one of the contributors above said I had 38% slippage, which I hope can be mitigated by the prop or the jack plate, but that will have to wait for now. I can afford a prop, but the jp would be $800 or so with a longer set of cables, so it will be plan B at this point. I have never used ethanol gas in this motor and the only non-ethanol gas on land is premium, thus more than regular land but a lot cheaper than lake non ethanol gas, but ugh, the 5 gallon gas cans and hoses and such, what a pain. Thanks for your info and suggs. I have never had a cheap hobby in my life, so these issues are no surprise to me. Such is the life of a captain. ed.
ps: yes, my hole shot is twice as fast as the 50hp, you are correct about the acceleration increase
