South Bay 522RS top speed

[Bamaman]

The old saying that you should be able to see your anticavitation plate doesn't hold any meaning on pontoons. My Express Tube hulled Bennington puts out some crazy water out of the tunnels--and my plate is not visible despite very low prop slip and good speeds.

Until you try a different propeller, raising or lowering your engine height is a moot point. And the Enertia is the standard of the industry for pontoon boats--available in 1 inch increments to perfectly set your needs.

[Ozark Bob]

We came very close to buying what you have, 24SSLX. Dealer at Pomme de Terre lake has some very fair prices on them. In the end the cost difference made the decision.

[Ozark Bob]

Here is and update on trying to get more RPMs and top speed. I installed a Quicksilver Q3 15.3 X 14 prop and did some test runs. At WOT I am seeing 35 mph at 5400 rpm. That's up from 32 mph at 5300 rpm. I can now trim to the limit with little are no ventilation and have to back the trim down just a bit to achieve best speed. Once I have the trim set I don't have to trim down in a hard turn. While I am happy with the performance and handling of the Q3 I would still like to get my RPMs up to the 5600-5700 range. My question is, do you think I could gain some RPMs if I raised the engine to hole #3 without any negative effects or should I leave it where it is? I am currently set in hole #2 and the engine rpm range is 5000 - 5800.

[Soonertoon]

Welcome to the club.

Heres some food for thought ...

First off, nice boat! You will get tons of enjoyment out of it for sure!
Having said that, its important to keep in mind you have a pontoon now...not a v hull runabout. You are literally pushing a refrigerator thru the water. Pontoons have evolved in last 10 years with lifting strakes to help get the old Frigidaire up on plane, a third toon to aid in buoyancy and act like a center keel in a runabout and ever increasing amounts of horsepower to make it all work. The addition of the 3rd toon equals more weight and increased drag, therefore requiring more ponies to push it. Its self fulfilling prophecy in some ways. However you are still pushing a refrigerator thru the water. That ain't ever gonna change .
There are some that will spend literally thousands of dollars chasing the illusive top end numbers. Always tweaking, always searching for the extra mile or two in top end speed. Like a dog chasing its tail....when the reality of the matter is, most folks don't run up and down the damn lakes all day at WOT. And you probably wont either. Its a pontoon not a v-hull. you could probably dick around , spend a wad of money and get a couple or three, four or five more out of it but in the end is it really worth it? Ehhh? Ask yourself how much time to I spend running WOT? also, which is more important? ?Usable power thru all the RPM range or top end?
If I were you, and Im not, what I would be concerned with is dropping that pitch down to a number that will get you RPMs in the correct range at WOT. I believe that is something in the area of 6k RPM. For every drop in pitch you should get an additional 200 rpm. Your motor will thank you and you will have more usable performance all up and down the RPM guage .
Your motor height, I would leave as is.

Anyway as I said ...food for thought.

[rancherlee]

Don't hurt to try one more hole up, basically free performance if you do it yourself and it works. If your getting 5400 with a 14p a 13p version of the same prop would be in the 5800rpm range. Personally I'd find the happy engine height first before playing around with more props. The Mercury 150 has a fat HP range so I wouldn't try too hard to find the perfect prop that gets you to max RPM. Unlike my Suzuki 140 which needs spin max rpm to reach the rated hp with a narrow 5600-6200 range.

[Ozark Bob]

Thanks for the feedback. I'm pretty sure this is the prop I am going to stick with. I am happy with the improvements in speed and handling and I don't want to keep throwing money at props. I am in the middle of the power range, 5000-5800, for the Mercury 150 four stroke so I think I am okay there. Just wondering if I could expect an increase in RPMs if I raise the motor 1 hole or if like Soonertoon said I'm just "chasing my tail"....

[Soonertoon]

You MAY, and I mean MAY, gain a slight amount of RPMs with a hole raise simply due to the reduction of drag . It wont be a lot but it may be slightly more. I have a two log 23 ft footer with a 115 Yamaha. AT WOT on a glass smooth surface , I can punch a whopping 30 mph GPS with 3 folks and half tank of fuel. MY RPM's are at 6100. I raised my motor 2 holes as when I got the boat it was in the very bottom hole. At speed, the damned water was coming up past the cover seal line and puking back into the transom. found out they did this as the tri toons are a lot of times put in the lower hole due to increased buoyancy. Two holes up was too far as I had literally no trim room before it cavitated. I split the dif and went to one hole up. Looks like this was the right location as my issues stopped on both fronts.. Plus it was a helluva lot easier to steer...lol
I don't recall if I gained any RMPs out of it or not. Im pretty sure I didn't but again that was just my experience. Yours may be different. Like the man said, its a cheap fix for managing the water flow around the motor but I don't think its gonna give you the magic RPM increase you are after. That's only going to come from dropping the pitch, or going to a different blade of prop. Some props are just harder to turn than others. A pitch drop will do two things for you right off the bat. 1. correct top end range and I mean the middle or top end of that range. 2. Better hole shot and on plane quicker.
But in the end..its still a refrigerator you are pushing thru the water.

[Ozark Bob]

Thanks again for your thoughts. Weather permitting, I hope to get out tomorrow and do some more test runs before I make any changes. If I can verify that I'm not getting any ventilation, or very little, I think I will go ahead and try raising the motor one hole. I'll report back on my findings.

[Soonertoon]

So, how did all this end up?

[Ozark Bob]

Some things have come up, mostly weather, and I haven't had a chance to get out. Hopefully next week.