Changing Pitch?

[agallant80]

I think I may have the wrong prop pitch on my boat and was wondeirng if I should go up or down.

About the boat
2013 Bayliner 255CR 6,800lbs dry with 5.MPI making 260HP running Bravo 3. 30MPH is about 4KRPM

This issue:
I know the boat is a bit underpowered t begin with. I have to pretty much put the throttle all the way down to get her on plain. If I drop much below 3,700 RPM she will fall off of plain. Once on plain the boat will easly exceed WOT which is 5,000RPM. When I say easy, I mean easy tap the lever forward a bit and the engine spins right up without struggle.

My questions is:
Is this the nature of the beast considering the HP and weight of the boat?
Do I need to go up or down in pitch if I can do anything about it.

 

[Sea Rider]

Once on plane the boat will exceed 5 K, is that with you alone and lightly loaded boat ? Need to post MAX wot rpm under flat calm no wind water cond no matter if engine is over revving, it's for a short time run. Then will know if in need to play with prop pitches and by how much. You should install trim tabs to make the boat plane faster.

Happy Boating

 

[alldodge]

I think I may have the wrong prop pitch on my boat and was wondeirng if I should go up or down.

About the boat
2013 Bayliner 255CR 6,800lbs dry with 5.MPI making 260HP running Bravo 3. 30MPH is about 4KRPM

This issue:
I know the boat is a bit underpowered t begin with. I have to pretty much put the throttle all the way down to get her on plain. If I drop much below 3,700 RPM she will fall off of plain. Once on plain the boat will easly exceed WOT which is 5,000RPM. When I say easy, I mean easy tap the lever forward a bit and the engine spins right up without struggle.

My questions is:
Is this the nature of the beast considering the HP and weight of the boat?
Do I need to go up or down in pitch if I can do anything about it.

I think your trimmed up to much, and possibly your stern is to far out of the water from your tabs.

How is the boat loaded, meaning how many people, where is the weight? Where are your tabs at?

When your on plain, you should increase trim until the boat starts loosing speed, then trim back down

 

[agallant80]

Most of the time its just my wife and myself on the boat. I do have tabs and use them though I have played with them and the outdrive trim and its still the same result. I have gotten the motor up to about 5400 RPM before and it has more to give but I don't want to push it as the guardian system starts beeping away.

 

[alldodge]

I'm not sure you can fix it. You need the low pitch prop to get up on plane. If you go lower you can get up faster but then rpm is the issue, if you go up you will have a heck of a time getting up. Add more weight and again you have more trouble getting up. Your issue sounds just like mine before I added more power.

My 10K cruiser came with a single (7.4L) 330HP engine and B3. So long as it had a half tank of fuel and just two people it would get up, sort of ok. Had also to run the engine hard to keep it going. I hated to have to slow down because getting back up was an issue. When we had other folks on the boat we would ask them to move to the forward cabin until we came up on plain. Replaced the 7.4 with an 8.2 and the problem went away except when we had a 7 or more full size folks.

I don't see how to fix it without more power, either with another engine or something like a whipple charger

 

[Starcraft5834]

Commander.........4 blade prop will help u stay on plane at reduced speed......if your running a 3 blade now. 4 is the ticket...... I don't have nearly the boat you do.. however same problem on a lower scale.. 20 ft cuddy w 3.0. had a 3 blade prop, took forever to get on plane...put a 4 blade prop on, shot out of the water in less than 5 seconds, stays on plane at reduced speeds... they ( 4 blade props) do make that much of a difference... that in combination with tabs might just be the winner........

 

[Sea Rider]

If wot rpm is 5 K, and you're going at 5400 hitting the rev limiter and with more throttle to go, then you need at least one more pitch size to lower your top rpm down to near or at safe 5 K rpm. With new prop fast hole shot could be a problem, no issue going full throttle until on plane, then can reduce throttle to maintain combo on plane. If boat is under powered will need to carry less load or passengers factory stated for. Something you can live with.

How about sending wife up front and testing on flat calm, no wind water cond with least fuel on tank, just to check if performance betters with new prop. A 4 blade prop or a variable pitch prop should take much better care of your existing boating issues.

Happy Boating

 

[mnm99]

I have a Monterey 26ft cruiser, 260hp , B3 drive. If you go with a 4 blade at the same pitch two things will happen.One, your RPM will come down a couple hundred =Good and second you will be MUCH better out of the hole and cruise = Good. I currently had the same problem with 6 people in my 26ft cruiser. I went from a 26p B3 prop to a 24P 4 blade and it's night and day. I lost 200rpm or so( old prop wasn't 26p i am thinking) RPM so I'm dropping to a 22P and that should bring me up. Trust me 4 blade props WORK. much better bite. I bought mine from Hill marine. Google them. Very nice props. I shoot out of the hole now, cruise at 30mph at 3300rpm and top speed of 36 at 4000rpm with the 24's. The 22's I should be able to cruise at the same speed at around 3500rpm, top speed should stay the same at 4400rpm and the hole shot should be insane. Good luck.