Purchased our new toon. Have some beginner questions.

[dubya1982]

We have been looking for about a month now and finally purchased our first boat. We wanted to be able to pull a tube and possibly a skier, so we ended up getting a 115hp. We purchased a new 22' Bentley 220 SE with 115hp 4 stroke Mercury motor. It has 25 inch toons. No lifting strakes.

We dropped it in the water on the way home from the dealer and I was a little disappointed with the top speed. On the GPS I was topping out at 22mph at WOT. I thought we'd be able to get a little closer to 30mph with this motor. Of course, I'm a beginner at everything boats, so maybe I wasn't driving it correctly (still trying to figure out the whole trim up/trim down thing).

Does this sound right to you guys? The wind was fairly calm and water was a little choppy, but not too bad.

The propeller is the aluminum one that came with the motor and I know you all recommend changing it. But even changing the prop it doesn't seem like it can increase the speed all that much?

I'd sure appreciate some feedback from some vets who know more about boats than I do. If this is the top end speed I already regret spending the extra cash for the bigger motor.

 

[natedog337]

Re: Purchased our new toon. Have some beginner questions.

We have been looking for about a month now and finally purchased our first boat. We wanted to be able to pull a tube and possibly a skier, so we ended up getting a 115hp. We purchased a new 22' Bentley 220 SE with 115hp 4 stroke Mercury motor. It has 25 inch toons. No lifting strakes.

We dropped it in the water on the way home from the dealer and I was a little disappointed with the top speed. On the GPS I was topping out at 22mph at WOT. I thought we'd be able to get a little closer to 30mph with this motor. Of course, I'm a beginner at everything boats, so maybe I wasn't driving it correctly (still trying to figure out the whole trim up/trim down thing).

Does this sound right to you guys? The wind was fairly calm and water was a little choppy, but not too bad.

The propeller is the aluminum one that came with the motor and I know you all recommend changing it. But even changing the prop it doesn't seem like it can increase the speed all that much?

I'd sure appreciate some feedback from some vets who know more about boats than I do. If this is the top end speed I already regret spending the extra cash for the bigger motor.

Most likely it's the pitch on your blade. I have a 26 foot sweet water yami 115 gives me 27-30 mph depending on conditions. When I purchased the original prop was only giving me 19mph. I swapped it out for a solas 4 blade 13 pitch and got 10 mph more. Unsure of the pitch on my original prop cause it had no markings on it. I'd start there I bt that is prob your issue you shod be pushing 30+

 

[dubya1982]

Re: Purchased our new toon. Have some beginner questions.

Most likely it's the pitch on your blade. I have a 26 foot sweet water yami 115 gives me 27-30 mph depending on conditions. When I purchased the original prop was only giving me 19mph. I swapped it out for a solas 4 blade 13 pitch and got 10 mph more. Unsure of the pitch on my original prop cause it had no markings on it. I'd start there I bt that is prob your issue you shod be pushing 30+

Is there a guide or something to help me find the best prop for my boat? How do I find out what prop will get me the best results with my setup?

I just went and looked at my prop and Googled it. I have a Quicksilver 3 blade 14x10RH with a 10 Pitch.

 

[MaPaHa]

Re: Purchased our new toon. Have some beginner questions.

The first thing I would do is find the max RPM that motor is rated at and I wouldn't be surprised if you are running RPM's that are too fast for that motor with the prop you have. I'm sure they pick a "generic" size that is suitable for a wide range of conditions. There's not a perfect size and style prop for all conditions so you have to pick one that's right for you. For instance the one you have may be set for a heavy load but does not top out well for speed. It seems that a 10 pitch is too small for much speed. When I put my spare prop on my 22 foot with an older 140 hp motor I lose a lot of speed.

I did a bunch of research before buying my prop and sent it back once for fine tuning. It's a stainless steel four blade from a company called Power Tech located in Louisiana and they have a great staff that can help in the selection process but you will have to give them the boat specs and some RPM numbers of existing performance. As far as what speed you can expect it's hard to say but I would think you could see some improvement.

The lifting strakes do make a difference and the dealer may be able to add them and maintain you're warranty but you would have to check with them. If you do, you would most likely have to change the prop again to reach the max performance. I added strakes to mine but it's an older boat and warranty isn't an issue.

There are things you can do to help the speed but you'll start spending some $$ to do them. One thing is skinning the underside of the boat so the water doesn't hit the floor joist. Check out the other threads on this in the last few days. If you did the strakes, skinning and the right prop you would have a different boat for sure. The prop will cost you 300 - 500 dollars and you would most likely have to do it again if you add strakes so I would decide on the strakes first. I would at least ask for a price on the strakes and who knows, they may do you a deal to keep their customer happy. The other problem with tubing is you have to make turns in which strakes will help also. If you told them you wanted to ski behind the boat before you purchased it they should at least work with you to get the right stainless steel prop. If the 115 was the bigger motor I don't think you went wrong because if it was smaller you wouldn't have much of a chance in getting where you want to be.

 

[Silvertip]

Re: Purchased our new toon. Have some beginner questions.

There is a prop forum here. However, before you start spending money on props you need to learn to run the boat properly.
1) Know when to trim up/down and how much to trim/up and down. The seat of your pants tells you that.
2) Maximum engine rpm at wide open throttle (WOT) should be about 6000 RPM.
3) Now make some WOT runs with what you consider an average load and with the boat properly trimmed.
4) Note the WOT rpm on the tachometer.
5) If the tach reads at or near 6000 RPM you have the correct prop although changing to a more efficient prop may give you 1 -2 mph it is probably not worth the expense.
6) If the engine is not capable of reaching its WOT rpm then you need a prop with less pitch. One inch of pitch change (up or down) changes engine rpm by about 200 rpm.
7) Understand that unless the engine way over propped, decreasing pitch will not likely increase speed much. Prop selection is all about getting the engine to run at or near its recommended WOT rpm for longevity and to avoid lugging it. Speed will be whatever that prop provides.
8) Lastly, If this rig is brand new, you had best follow the break in procedure to the letter and wait until the engine is fully broken in before worrying about props. Pontoons generally work best with pontoon-specific props which are almost always four blades with big rounded blades.

 

[lakegeorge]

Re: Purchased our new toon. Have some beginner questions.

We have been looking for about a month now and finally purchased our first boat. We wanted to be able to pull a tube and possibly a skier, so we ended up getting a 115hp. We purchased a new 22' Bentley 220 SE with 115hp 4 stroke Mercury motor. It has 25 inch toons. No lifting strakes.

We dropped it in the water on the way home from the dealer and I was a little disappointed with the top speed. On the GPS I was topping out at 22mph at WOT. I thought we'd be able to get a little closer to 30mph with this motor. Of course, I'm a beginner at everything boats, so maybe I wasn't driving it correctly (still trying to figure out the whole trim up/trim down thing).

Does this sound right to you guys? The wind was fairly calm and water was a little choppy, but not too bad.

The propeller is the aluminum one that came with the motor and I know you all recommend changing it. But even changing the prop it doesn't seem like it can increase the speed all that much?

I'd sure appreciate some feedback from some vets who know more about boats than I do. If this is the top end speed I already regret spending the extra cash for the bigger motor.

You are absolutely right, you should be getting a lot more speed. We had a 22ft Sweetwater with a 60 yammy and got 21mph.
What rpm's are you running? did you try trimming out the motor? How many people were on board?
You should get an easy 27/29 mph and the dealer is the one who should be trying out props for you.

Go to the Mercury web site and type in Engine tests and you will find your motor and a lot of boats that they test with it, use that as a comparison, it will also tell you what prop they tested with also.

 

[lakegeorge]

Re: Purchased our new toon. Have some beginner questions.

Dubya, I just went to the Mercury web site and they have a 22ft Bentley with the 115 hp motor and it ran 30.1 mph at 6,200 rpm's with the 14x11 Aluminum prop. Check it out.

 

[Bamaman1]

Re: Purchased our new toon. Have some beginner questions.

This is a duplicate posting.

I agree that it's a dealer's responsibility to properly prop your boat. And it's difficult to do with no hours on the engine because four stroke motors especially need to be properly broken by factory instructions before spinning up to max rpm's.

 

[Capt Sully]

Re: Purchased our new toon. Have some beginner questions.

guess I'm doing good, my 90hp gets me up to 24mph, fast enough for me, all I do is anchor/float and relax, maybe some fishing now and then :fish2:

 

[WaterDR]

Re: Purchased our new toon. Have some beginner questions.

Is there a guide or something to help me find the best prop for my boat? How do I find out what prop will get me the best results with my setup?

I just went and looked at my prop and Googled it. I have a Quicksilver 3 blade 14x10RH with a 10 Pitch.

10 pitch is entirely the wrong prop! I suspect that you were not only at wot but hitting the rev limiter. You will need a 13 or even a 15 and yes, you should be seeing something around 30.

 

[dubya1982]

Re: Purchased our new toon. Have some beginner questions.

10 pitch is entirely the wrong prop! I suspect that you were not only at wot but hitting the rev limiter. You will need a 13 or even a 15 and yes, you should be seeing something around 30.

What is 'rev limiter'?

It was running at very high rpm, higher than the book recommends.

We are going out tomorrow and going to do a little more breaking in. I will record the rpm results and get back with you all.

I appreciate the responses. And as someone mentioned earlier, I'm sorry for the double post. After I posted this I reposted in the Props forum because I realized it was more of a prop issue.

 

[Lurch77]

Re: Purchased our new toon. Have some beginner questions.

A rev limiter is a safety mechanism, either mechanical or electronic, built into the engine to prevent it from revving faster than is mechanically safe. Prevents engine damage. If your engine was running higher RPMs than what it should be, that suggest you do not have enough prop pitch.

 

[WaterDR]

Re: Purchased our new toon. Have some beginner questions.

What he said.

The best way to know if you have the right pitch, is that you want to be hitting near the max rpms, but not exceeding it and not hitting the limiter.

How many rpms were you running?

 

[dubya1982]

Re: Purchased our new toon. Have some beginner questions.

Well we got the boat out on the lake today and had a great time. It was pretty windy today and the water was very choppy. We had 4 adults and two kids on the boat.

When I opened it up all the way the most I could get to was 21 mph. Last time we were out we only had 2 adults and one child and I was able to get to 22 mph. So not a significant difference. The water was much calmer the first time too, much calmer than today.

When I was at WOT I our RPM was maxing at 6400. It wouldn't go past that. I looked in the manual and it says that the engine is wide open and safe at 5800 - 6400 RPM. It says that you shouldn't run it past 6400.

So what do you guys think? We were hitting that max RPM, but still not getting any speed like most said we should expect from the 115.

 

[Old Screwball]

Re: Purchased our new toon. Have some beginner questions.

Are you still running that 10 pitch prop??? If your tach says you are turning 6400 RPM, I'd bet it is your rev limiter that is holding that rpm. I have a 75hp Merc on my 18' Party Barge. If I run at WOT the best I can get is 5800 rpm with a 13 pitch prop. The propeller, pitch, and water force are holding me at 5800 rpm, not the rev limiter. Go to anywhere that sells propellers, most have a work sheet to help you select a propeller. It would be my guess you need an 11 or 13 pitch.

 

[dubya1982]

Re: Purchased our new toon. Have some beginner questions.

Are you still running that 10 pitch prop??? If your tach says you are turning 6400 RPM, I'd bet it is your rev limiter that is holding that rpm. I have a 75hp Merc on my 18' Party Barge. If I run at WOT the best I can get is 5800 rpm with a 13 pitch prop. The propeller, pitch, and water force are holding me at 5800 rpm, not the rev limiter. Go to anywhere that sells propellers, most have a work sheet to help you select a propeller. It would be my guess you need an 11 or 13 pitch.

Yes, I still have the original prop that came with the boat. I just bought the boat two days ago so I wanted to run it and get the numbers to find out the best way to go.

So if I have a 10 pitch and I am running at the max recommended RPMs does that mean that I need more prop? From what I understand reading the posts each number up in pitch will bring down my RPMs by about 200. So if I get a new prop with a pitch of 12 I can expect to bring my RPMs down to around 6000 and possibly increase the speed because it is running more efficiently?

 

[MaPaHa]

Re: Purchased our new toon. Have some beginner questions.

Before I would buy a new prop I would use one of the prop calculators on line to help you determine where you are now and then get with a good prop shop that can help you select the best one for the boat and your usage. If the place you deal with for the prop doesn’t ask or know what the gear box ratio is for you’re motor then I would find someone that knows what they’re talking about.

You can figure it manually if you want but you still need the gear box ratio. To get a better feel for what the pitch really means, here’s my take on it. If it’s a 10 pitch prop then every revolution moves the boat 10 inches if there were no slippage.
If your engine is turning 6400 rpm and you have a gear box reduction of 2:1 from the engine to prop then the prop is turning 3200 rpm. Then do the math to calculate the “perfect” speed. 6400 x .5 gear box ratio = 3200 prop rpm; then 3200 x 10 inches = 32,000 inches per minute; then divided by / 12 inches per foot = 2666.67 feet per minute; then x 60 minutes per hour = 159,999.99 feet per hour; then divided by 5280 feet per mile = 30.30 MPH. This is the “perfect” speed based on these calculations and you will never achieve this speed because of prop slippage. Then you have to apply a slippage factor to that for you’re real speed.

Remember I used a gear box ratio of 2;1 only because that’s what mine is so this may not be you’re ratio. However, if this is you’re ratio I think you can see that you’re boat will never see 30 MPH with that prop. If you could limit you’re slippage to 15% with a stainless steel prop then 30.30 x .85 = 25.755 MPH.

If this is you’re ratio then take the speed you listed of 21 MPH and divide it by the perfect speed. 21 / 30.30 = .693 or slippage of about 31% which is a lot. Again this is based on a 2:1 gear box. I ran mine yesterday and calculated the speed and slippage at several different RPM’s but at full speed of 5,500 RPM I got a 14% slippage or .8642 factor. I have a high end four blade pontoon style prop from Power Tech. I imagine an aluminum prop would have considerable more slippage.

Hypothetically (based on a 2:1 gear box) if you switched to a good 12 pitch prop and the motor slowed down 400 rpm then: 6000 x .5 = 3000 prop RPM x 12” = 36,000 in. per minute / 12 = 3000 ft. per min x 60 = 180,000 ft per min / 5280 = 34.09 MPH perfect speed x .85 slippage factor = 28.97 MPH. That’s assuming the motor will pull it at that speed. With a 10% slippage: 34.09 MPH perfect x .9 = 30.68 MPH

I would consider a good 13 pitch stainless for a pontoon boat from a company that can modify it for a small fee if that’s too much or too little prop. They can usually change the pitch about one degree either way but check with them before you buy one because they are $350.00 – 450.00 dollars. More than likely an 11 pitch will leave speed on the table and a 13 pitch will lug the motor down. If they know the facts going in then they probably won’t charge for the modification. Unfortunately finding the right pitch and modification is done by trial and error.

Not to sound like a broken record… but I can’t say it enough to deal with a real prop shop rather than an ordinary boat dealer. If you’re dealer will do it for free then go for it, see what you can get and build from there, but if they want to “upgrade” you’re prop for a sizable fee then go with you’re instinct.

Hope this helps,

 

[WaterDR]

Re: Purchased our new toon. Have some beginner questions.

It's simple...if you are hitting the rev limiter the 200 rpm per pitch rule won't matter anyway. Checkout Merc website and look for similar boats with same motor. Go back to the dealer and simply ask if you can swap the prop out. If it were me, I would try a 13p aluminum. If the rpms on the 13 drop, then you have the right prop provided it is between 5800 and 6200. If its still spinning at 6400 then try a 15p.

If the dealer is not convenient, then find a local prop shop and see if they have a loaner you can use. Most of them will allow you to buy a prop and return it if it is not damaged.

Once you have the aluminum dialed in, and if you want to get a stainless, you can go that route.

Props are trial and error.

 

[WaterDR]

Re: Purchased our new toon. Have some beginner questions.

Btw, I have a 115 yam with a 24 ft toon and run a 15p alum and 13p stainless. Boat runs 30 mph.

 

[BobGinCO]

Re: Purchased our new toon. Have some beginner questions.

I have a 115 Merc (which only delivers about 90-95 HP at the elevations I run), with a 13.75 X 13 pitch prop and I get 23 MPH on my 3,000 pound 24' tri-toon. The dealer (in Minnesota - much lower elevation) sells this configuration with a 15 pitch prop - but that's too much for my elevation.