Pontoon Boat & Deck Boat Forum

I have a 25 foot crest pontoon with a 90 Horse 2 stroke and the best I have gotten out of it is about 13-15mph at wot(5500 rpm) does this seem a little slow ??

I get 20 - 21 WOT 4900 RPM 24' playcraft so to me its a little slow. Hope that helps.

I just gps'd mine a couple weeks ago.
23 mph with 4 people, cooler, and 3/4 tank of fuel. This was on a pretty choppy river.
24' Triton with 90 Optimax Merc.

Ernie

You should be hitting 20-22.

I have a 24 foot Bentley with a 90 2 stroke Merc. and get 26-27mph on the gps at WOT with me and my little girls in calm water with clean toons. The girls are very light and no cooler on board. I usually check it for fun after scrubbing the toons since the boat lives in the lake.

The 2 underlying factors that will effect speed differences in pontoons of like HP and length and configuration is prop selection and total weight of the boat and cargo/passengers. 5500RPM is a bit low for a boat with one person in it. 5300/5500 with a few people wouldn't be out of the ordinary. If your lugging a lot of extra stuff onthe boat, that will effect things some. Dirty logs, water logged furniture lots of towels, water toys all add up. I would clean the logs with a couple of magic erasers, empty the boat with the exeption of a few PFD's, then give it a run in calmish conditions, and see where you are at. Check your prop size and condition. When was the last time the motor saw a tune up? Just open ended questions to ask yourself. Yes, your speed is low for that combination of boat and motor. As stated 20-21 should do it.

A good example of weight and it's effects:
1. my boat 2013 22' Sanpan with 27" logs. 115 Yamaha 4 stroke. Boat weight is 2870 with motor. 24.5 GPS is all she will do with 2 people.
2. Friends boat 2011 Sweetwater 22' with 23" logs 90 Yamaha 4 stroke. Boat weight is 2320 with motor. 27 GPS same conditions, same lake.
So, smaller motor, but faster boat. Both motors rev to 5800 in above conditions, so both are propped fine. It's the weight that is killing my top end. When the logs can't get the nose cones out of the water, the boat goes slow. Full, vs half tanks make a little difference, but most of that weight is in the back which helps with CG.

Well the boat is a 25 footer, and even with just two people and half a tank of gas its slowwww.... The motor is 1986 88spl rated at 90 horse. Not sure what the prop is, but at WOT it turning 5500 and only going about 15 mph.. Seems to be running alright. and I only run the non ethenol fuel in it. The motor looks brand new under the cowl, so I figure the past owners must have had it serviced regular. Mabey the prop is just wrong

The motor looks to be sitting in the transom a bit low.does it have adjustment holes to change motor height? If it does, try raising it a bit. Some older motors were rated very optimistically, not saying this is the case, but,,,,the motor may not be laying down what it claims. Without knowing what the design peak HP RPM is, we are shooting in the dark. 5500 sounds low. Motor may be sitting too low, prop may be too heavy of a pitch, or its just not a real strong motor. A new rated 60 will get you 17-18 mph for comparison on a boat that size. Also if you measure the deck on that boat, it's probably about 22 feet long. Some boats seem shorter than others because the manufacturer measure them from different reference points. Apples to apples I would say that boat assimilates a 22 footer. It's just got a long transom. My old Bennington was the same way.

Water in toons

22 feet. Inside of the playpen and 25 feet from deck to deck, and I noticed that the motor seems to be a little low in the water. When at full speed and even trim the water is almost up to to bottom of the actual motor its self. I usually trim it up a little to keep the water from coming up over the transom itself. How much does that make a difference. I'll try to get a picture of it this week.

Your RPM are right on the money per service manual 4500-5500 RPM WOT but it sounds like the motor is setting to low, you want the cavitation plate to be just under water while under way at WOT. Oh BTW this motor is a gas pig IMO.

Yes it does like to drink deeply when at WOT.. I bet somewhere in the range of about 2 miles per gallon or less.. lol.. It does have holes for moving the motor up I beleive.. Now to see how to get it out of the water to move the motor and try it. Cant Hurt to try.. The plate is under water at wot, like probably several inches.

readbeard, can you get me a picture of what it looks like where your motor is setting just for a comparison, we have a pretty similar setup.

Been looking for pic of what you wanted let me know if these help, I've been working on a full set of pic's so I have them on hand but the boat is 120 miles away maybe some day I'll have them all.

Thanks Man that helps alot.. I will look this weekend and snap some pics to see where mine is at.. I am sure its alot higher than that.. I may have to see if I can get someone with a trailor to come get it out of the water so I can lift the motor a couple of holes and see how it goes.