Pontoon Boat & Deck Boat Forum

I have a 2002 Palm Beach pontoon with a Mercury 50. Does this motor seem to low? I can be underway on the water and it will run fine the it blows out all of a sudden. Rpms go up and boat slows down. Back off throttle and back to cruising. It happens at random times. I thought maybe the motor is to low. Please help thanks

Sounds like the motor is too high. Drop it down a hole or two and see if that helps.

Thanks for the help but the motor is at its lowest point.

If it is at its lowest point then try a hydro foil, they can help with cavitation at times.

jonboy2542 wrote: ↑

Sat Jul 18, 2020 12:39 pm

I have a 2002 Palm Beach pontoon with a Mercury 50. Does this motor seem to low? I can be underway on the water and it will run fine the it blows out all of a sudden. Rpms go up and boat slows down. Back off throttle and back to cruising. It happens at random times. I thought maybe the motor is to low. Please help thanks

Is the bottom of your transom bent up on purpose? I don't think I've seen that before.

i've been fighting with ventilation issues myself. I have a 60hp merc that was mounted at the top holes (motor at the lowest setting). My cavitation plate was pretty low compared to the bottom of the transom. I raised the motor two holes and saw a little bit of difference in a good way. raised it up to the two final holes and I think we're good. at WOT I can see the cavitation plate . I also have reduced water being flung over the motor.
so I say raise it up!

Your cavitation plate should be at or near bottom of mounting pod--you look--5-6 inches too low it looks like. Solutions if you cant raise it are to get a shorter lower unit motor or use blocks to raise transom as long as you can still use the upper mounting holes

Sorry Wwind but that’s not correct. On a tri toon the cavitation plate should be in line with the bottom of the toon same as a mono hull but with a pontoon the cavitation plate height varies greatly depending on the boat design and weight distribution. He has already said that he is blowing out at top speed so he need more water not less. Since he cannot go lower without replacing his lower unit a hydro foil is his best chance. That or modifying his transom to get the engine lower.

Like being stuck between a rock and a hard place. Its hard to believe that it needs to be lowered more. This is my first pontoon and before this; just bass boats. This is becoming confusing. If i drop the motor more i would lose RPMs. Currently i am only getting 4000 rpms. Just curious mainly because i dont know; why would I lower the motor more if its in the water deep as is? I always thought it would need to come up.

Joseph was commenting about a tritoon but you have a regular pontoon (you don't have the third pontoon leg) so that doesn't apply to you. I still say to raise it up...your motor and my motor look like they were in the same spot, kinda low. I raised mine all the way up (but did it a little at a time) and now it's running like it should...so far no blowouts and rpm's increasing.

Joseph Elliott wrote: ↑

Tue Jul 21, 2020 10:45 am

Sorry Wwind but that’s not correct. On a tri toon the cavitation plate should be in line with the bottom of the toon same as a mono hull but with a pontoon the cavitation plate height varies greatly depending on the boat design and weight distribution. He has already said that he is blowing out at top speed so he need more water not less. Since he cannot go lower without replacing his lower unit a hydro foil is his best chance. That or modifying his transom to get the engine lower.

He's blowing out because the lower unit is breaking up the flow of water around the prop--it's like stalling an airplane wing---the smooth flow of water/wind is interrupted. I can trim my motor up a crazy amount without it blowing out. I can take off with the motor tilted without it blowing out--and in winter when the water is cold/dense I can hit 29GPS with my aluminum 16P prop. Maybe I just got lucky....

^^^^^^^^
this...yup!

Looks like a motor with a 25" shaft on a boat/transom made for a 20" shaft. Agree with wwind3 on the reason for the blowout.

If at best you are only getting 4000 rpms you have the wrong prop. That height doesn't look terrible. A 2 log boat is tough because the prop is never in "hard" water like a v hull or even tritoon. If you are pitched too high you'll be super finiky with getting a good bite in the water. What is the hole shot like? Does it jump to life or climb to rpms slow? How is the boat loaded, weight distribution? What prop size do you have currently? A few details can help with better advice. Raising the motor will not help with blow out that's for sure. I'm honestly a huge fan of 4 blade props on a pontoon. Might loose a mph but the hook up half out of the water. My most important question is what prop only gets you 4000rpms at best?

As far as hole shot, not the best but not the worst. It climbs up on rpm but its not fast. Coming out of a no wake zone and give it throttle, it just climbs up to 4000 rpms. The interesting thing is that it acts the same with 4 people as it does with 10 people.

The motor is a 2002 Mercury 50ELPTO
Prop is a solas 1311-110-15
22 foot palm beach

I would love to add a 4 blade but with the way things are right now, not the best time to be buying a prop. When i do, I may drop put a different pitch on it.