need help selecting the right prop

[kentuckyguy]

I have just purchased a new 2010 21 foot Triton Seabreeze pontoon.. It has a 90 h.p. merc 2 stroke.. Right now it is a 13 3/4x13 prop.. The engine will turn 6200 rpm (wot).. The boat shop told me not to run it over 5750 rpm.. The tag says 5500 rpm.. Anyway the boat will GPS at 25mph.. I need to go with a higher pitched prop to get the rpm down but dont know if I need to go with a 15 or a 17 pitch..What would you recommend.. Any guess as to how much speed the boat will pick up?? Oh.. It does have 25 inch logs...

 

[Rancherlee]

Re: need help selecting the right prop

Is that RPM Empty? If so I would stick with it until you try it with a heavy load. A 15 pitch might get you around 5700 like you want but may drag down the RPMs too much with a heavy load. You could go to a 4 blade 13 pitch also which would be somewhere between the two. Its all trial and error, maybe your dealer has some other props you could try out?

 

[EGlideRider]

Re: need help selecting the right prop

+1 for Rancherlee.

 

[kentuckyguy]

Re: need help selecting the right prop

Is that RPM Empty? If so I would stick with it until you try it with a heavy load. A 15 pitch might get you around 5700 like you want but may drag down the RPMs too much with a heavy load. You could go to a 4 blade 13 pitch also which would be somewhere between the two. Its all trial and error, maybe your dealer has some other props you could try out?

I had the boat loaded over the weekend and it still did 6200 rpm@22mph.. The 25mph is with me only and a small cooler..

 

[EGlideRider]

Re: need help selecting the right prop

With a new boat, I would insist that the dealer provide you with the right prop. Having said that, I think a 15 will be too much for your set up. I would insist that the dealer let you try a 4-blade 13 pitch or rebuild your 13 pitch with a 'pontoon cup'.

Regardless, I see this as a dealer problem and they should make it right.

 

[kentuckyguy]

Re: need help selecting the right prop

With a new boat, I would insist that the dealer provide you with the right prop. Having said that, I think a 15 will be too much for your set up. I would insist that the dealer let you try a 4-blade 13 pitch or rebuild your 13 pitch with a 'pontoon cup'.

Regardless, I see this as a dealer problem and they should make it right.

Oh they are gonna.. They told me that I could trade it out for a different one... The problem is that the dealer is 40 miles from me and I dont wanna be makeing several trips back an forth..

 

[kentuckyguy]

Re: need help selecting the right prop

Any help??

 

[hckplyers]

Re: need help selecting the right prop

Do you have lifting strakes?

Is your cavitation plate even with the bottom of your center tube?

It should be there at least or slightly lower, if too low it will cause drag at take off, slowing hole shot, until you can trim up some.

I would go with at least the 15, with some cup added. But try that only after checking your motor height and making a few adjustments, this can be done at home actually, then take and try on the water, see how it feels, but only with you and one other person, make sharp turns, stop, then take off like pulling a skier. See where you find the sweet spot with your adjustment. Then see where your rpms are falling, that is when you might make a prop change.

As rancherlee said, with a load your rpms may fall too far with a 15 pitch, making it bog down, but then you stated the rpms were still high with a fairly good load with the 13. You may find that the 15 is the right prop, but check the motor height, we had ours lowered two times and went with the power prop, lower pitch, as we do more water sports, but with the higher pitch prop, we can really move when alone, but the hole shot isn't so good and can't plan off when hauling lots of bodies.

Always have a spare prop, it isn't if you will need it is when you will need it.

 

[kentuckyguy]

Re: need help selecting the right prop

Do you have lifting strakes?

Is your cavitation plate even with the bottom of your center tube?

It should be there at least or slightly lower, if too low it will cause drag at take off, slowing hole shot, until you can trim up some.

I would go with at least the 15, with some cup added. But try that only after checking your motor height and making a few adjustments, this can be done at home actually, then take and try on the water, see how it feels, but only with you and one other person, make sharp turns, stop, then take off like pulling a skier. See where you find the sweet spot with your adjustment. Then see where your rpms are falling, that is when you might make a prop change.

As rancherlee said, with a load your rpms may fall too far with a 15 pitch, making it bog down, but then you stated the rpms were still high with a fairly good load with the 13. You may find that the 15 is the right prop, but check the motor height, we had ours lowered two times and went with the power prop, lower pitch, as we do more water sports, but with the higher pitch prop, we can really move when alone, but the hole shot isn't so good and can't plan off when hauling lots of bodies.

Always have a spare prop, it isn't if you will need it is when you will need it.

No lifting strakes

This is not a tri toon.. The cavitation plate is right even with the bottom of the transom.. I run the trim just a bit above 1/4 mark on my gauge I have a good hole shot even with 6 people.. Today I was pulling 2 tubes with 2 people on each tube and 2 adults on the boat.. I was running between 4500-5000 rpm with a gps speed of 15-16mph.. (depending on rpm) Guess I will try a 15 pitch..

 

[kentuckyguy]

Re: need help selecting the right prop

Do you have lifting strakes?

Is your cavitation plate even with the bottom of your center tube?

It should be there at least or slightly lower, if too low it will cause drag at take off, slowing hole shot, until you can trim up some.

I would go with at least the 15, with some cup added. But try that only after checking your motor height and making a few adjustments, this can be done at home actually, then take and try on the water, see how it feels, but only with you and one other person, make sharp turns, stop, then take off like pulling a skier. See where you find the sweet spot with your adjustment. Then see where your rpms are falling, that is when you might make a prop change.

As rancherlee said, with a load your rpms may fall too far with a 15 pitch, making it bog down, but then you stated the rpms were still high with a fairly good load with the 13. You may find that the 15 is the right prop, but check the motor height, we had ours lowered two times and went with the power prop, lower pitch, as we do more water sports, but with the higher pitch prop, we can really move when alone, but the hole shot isn't so good and can't plan off when hauling lots of bodies.

Always have a spare prop, it isn't if you will need it is when you will need it.

What is cup added??

 

[kentuckyguy]

Re: need help selecting the right prop

Went to the boat shop this morning where I got the boat.. They didnt have a 13 3/4x15 prop in stock.. They gave me a 13 3/4x17.. I brought it home an put it on.. Went to the lake to try it out... Rpm at WOT was 5200 with a top speed of 28mph.. I tried the trim in several different places.. The sweet spot for takeing off was at 1/4 and cruiseing was a tade bit higher then that... I talked them them and they said that 28mph was a good speed an at 5200rpm I wouldnt burn as much gas... Guess I will try it for a while..