Pontoon prop questions

YuQQ

Cadet
Joined
Apr 30, 2010
Messages
9
I have a South Bay 522, its stated weight is about 1800 lbs. I have a 60 hp bigfoot on it and I am having trouble reaching max rpm @ WOT. I currently hit about 4700 with a 14 x 11 cupped prop. I am getting a 14 x 9 cupped after the weekend but I highly doubt that will get me above 5000 rpm.

I guess my question is what is the problem here? Is the boat to heavy for the motor? Is there something wrong with the motor? I have tried adjusting trim and it seems to have no effect, this setup is all new and its my first toon so I am kinda lost. Any help would be greatly appreciated, THX
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Pontoon prop questions

YuQQ, welcome to Iboats prop forum and we will try to help you as much as we can but without more information no one can help you, and I will tell you I need more information than anyone else. But if you would like my help fill this form out and I will help you as much as I can.

You might try reading this for a better understanding of changing props for better performance, and for the major differences between aluminum props and stainless steel.

http://forums.iboats.com/showthread.php?t=369057

If you would prefer to not go to this much trouble there are many other people who will come along and gladly help you.

1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
2a.What is the maximum recommended HP for your boat
3. Number of people and gallons of gas normally on boat and what do you use the boat for
4. Year, make. manufacturer and model of motor and recommended Wide Open Throttle (WOT) range
5. HP and gear ratio of motor IMPORTANT
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing then do the same thing on the flywheel and turn the motor until the tape lines up with each other on the prop, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
6. Anti-ventilation Plate height above keel of boat if it is an outboard in inches, use a straight edge under the keel and sticking out to the anti ventilation plate for a reference
Motor Transom Height
AntiventilationPlateStraightEdge-2.jpg

7. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. Make sure you trim the prop up until it starts ventilating and then just trim in until it quits ventilating.
RPM _________ Speed ______ GPS ______ No. of people ______ Gal. Gas ________
8. Make, model, diameter, pitch, number of blades and whether SS or aluminum prop and does it have a hydrafoil, dolefin or trim tabs
9. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way by just pushing the throttle at the helm and not at the carburetor, checked compression, and looked at the plugs and checked spark as well as timing and advance, all of the foregoing could be the reason your prop is not attaining full RPM
10. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations and does the prop show any damage that you can see

REMEMBER, The numbers I give you will be NO better than the information you give me. I use a computer program I designed to find the correct pitch and then knowledge to pick a Better prop design for your boat.

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.



H
 

YuQQ

Cadet
Joined
Apr 30, 2010
Messages
9
Re: Pontoon prop questions

1. 2010 South Bay 522 F
2. 23'7", 8'6",1760 # and motor is 260 #
2a. 115
3. 30 Gallons, 2 adults and 3 kids under 7
4. 2010 Mercury 60 hp Bigfoot, Wot 5500-6000 rpm
5. 60 HP, 2.33:1
6. 1 inch below
7. 4700, 18, gps, 2 adults 3 kids, 30
8. mercury, black max, 48 77338cp1 11p , 14, 11, Aluminum, it has cupped tips
9. boat and motor are brand new, I can push the throttle forward with my finger at the motor about 1/4 inch or a bit more with the throttle at helm pushed all the way forward
10. I want to be able to reach recommended rpm @ WOT, I plan on pulling tubes this summer and would like to have full power

plate depth

boat001.jpg
 

YuQQ

Cadet
Joined
Apr 30, 2010
Messages
9
Re: Pontoon prop questions

I did some looking and the throttle hits the throttle stop when its pushed wide open at the helm, so its not that I guess.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,348
Re: Pontoon prop questions

Ayuh,... The motor is mounted Too Low...
In your 1st picture, it appears to be Atleast 2" low,... Maybe More....
The Cav-plate should be Even with, or slightly above the bottom of the pod...
 

YuQQ

Cadet
Joined
Apr 30, 2010
Messages
9
Re: Pontoon prop questions

Ouch, I don't see how I might raise the whole motor by myself. Any ideas on the best way to raise it? It weights 260 lbs.
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Pontoon prop questions

Ok, the first thing we need to do is adjust the throttle advance position so that it opens the throttle all the way when it is pushed to WOT position to see what our max speed and RPM are right now.



H
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Pontoon prop questions

Yu, take the motor cover off, and there should be a fixture on the top of the motor so you an pull it up under a tree and use a come along to raise it.



H
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: Pontoon prop questions

Yu, take the motor cover off and there should be a fixture on the top of the motor that you can attach a come along to after putting it under a tree and that is how you do it.



H
 

YuQQ

Cadet
Joined
Apr 30, 2010
Messages
9
Re: Pontoon prop questions

Just an update. I put a 14 x 9 pitch uncupped prop on and I can hit 6000 rpm easy with going to WOT. It goes 17 Mph now and my trolling speed went from 2.5 mph to 1.2 mph. I plan on raising the motor tomorrow 4 holes which will bring it up 2 1/2 inches. The ventilation plate is currently 10 1/2 inches below the water line so moving it up will get me to 8. That will be the highest I can go without some kind of Jack plate (if thats what its called).

I think I will keep the 9 pitch prop for our fishing adventures but when it comes to cruising and tubing I guess I am lost at what to do to get the performance we should be getting out of this setup. Anyone have any ideas as to next step after I raise the motor?
 

YuQQ

Cadet
Joined
Apr 30, 2010
Messages
9
Re: Pontoon prop questions

Another update.

I raised the motor as high as it would go. The ventilation plate is now 1 inch below the transom.

I was using the 14 x 11 cupped prop and got 20 mph and 5100 rpm @ WOT.

I plan on getting a 14 x 10 cupped prop and see what that does but I think I am going to be stuck @ 5300 rpm or so @ WOT.

Below transom.

boat007.jpg


Measured.

boat008.jpg


Sorry about the quality but it was hard to steady.

Am I correct in assuming that 5300 rpm @ Wot with a cupped 14 x 10 will be max rpm with this setup, the best I can expect out of this boat and motor.

I don't see what more I can do.

A correction to my May 9th post. I hit 6000 rpm WITHOUT going to WOT with the 14 x 9 prop. Only about 3/4 throttle.
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Pontoon prop questions

The motor needs to go up. A Bob's 4-n-1 manual will open up a world of possibilities.
 

YuQQ

Cadet
Joined
Apr 30, 2010
Messages
9
Re: Pontoon prop questions

I read the post about people not responding so I thought I would update (yes 18 months and 300 hrs boating later).

I raised the motor, I started to get cavatation, slip, blowout whatever you want to call it in rough water while turning pulling tubes. I dropped the motor all the way down and left it. The water is such a mess at speed at the motor, its like there is no clean water for the prop to grab and I guess thats the nature of 2 tube pontoons.

I had a 14 x 10 prop and was getting 17 mph and 6000+ rpm @ WOT with the 5 of us and all our gear for the day, poles, coolers, tubes and all the little extras.

I took the 14 x 10 pitch prop to a local prop shop and explained what was going on. He told me what he was going to do to help and I picked it up 2 days later. He put just alittle cup on the tip of the blade where he said it would't effect rpm to much.

I now get 19 mph pulling tubes and 20 mph @ 5900 rpm @ wot just cruising. These differnces are not much but the boat feels so much more responsive, kind of like putting new tires on your car or truck.

Thanks for everyones input, it was a good learning experience. Now all i need is a 115hp to put on it because the kids want to go faster.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Pontoon prop questions

Calculater indicates 16% slip probably not bad for a pontoon.
If you haven't tried a 4 blade prop you might give one a try It may improve the slip
and should handle better and if it gets the slip down to 12% you might squeeze another mph out of it.
Also try balancing weight for and aft to the best speed.
 

Bamaman1

Lieutenant Commander
Joined
May 15, 2011
Messages
1,895
Re: Pontoon prop questions

If someone purchases a new boat, and it won't pull the redline or run up to expectations, immediately take it back to the selling dealer. It should be up to him to replace the propeller or re-rig the engine to where it doesn't ventilate.

Many manufacturers have tried different motor combinations, and they can tell a dealer the best prop for the application.

This is just not rocket science, and a customer shouldn't have to buy numerous after market propellers to come up with the best one for his purposes.
 

YuQQ

Cadet
Joined
Apr 30, 2010
Messages
9
Re: Pontoon prop questions

I agree they should have had the right prop on. I am not happy at all with the dealer and the prop was only one of the problems we had. I really don't even want to start off on rant about how bad our experience was with them. I love the boat though so I will leave it at that.

As far as a 4 blade prop , I will wait because I would really like to get a 115 hp on it. The kids are only getting bigger, and me too but thats a different story.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Pontoon prop questions

A 14x 9 elephant ear prop is what that engine should have had from the beginning. That is a pretty standard prop for 40/50/60 HP Big Foot motors on pontoons.
 
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