Prop Size Change

[Adam Costa]

Hello and good morning.
Recently picked up a 03' 17' roplene triump sc. It has a 04' Yamaha 50hp (Model: F50TLRC). Boat weighs 1,100.

Top speed is 30mph taching 5,200-5,300 RPMS. Boat has a 11.25" diameter prop with a 14pitch.

My issue is down low the motor has zero grunt and it really struggles to get up on plane. Maiden voyage was in a bit of chop and having to slow down to take big wake and come back to plane is a struggle. I'm looking for a prop suggestion to help the boat plane faster at the lower RPMS.

Thank you

 

[jakedaawg]

That's a small motor. First make sure your firing on all cylinders. Those run leaner and it's easy to lose a hole.

 

[Adam Costa]

Most certainly an under powered vessel. Motor was recently serviced by a licensed and reputable marina. Fuel system was gone thru, 2 carbs replaced. Marina owner is a certified Yamaha dealer/tech. In an ideal world- it'll have a 75 hp e-tech on it someday. But for now I need to make adjustments for the low end.

 

[Sea Rider]

You can?t possibly plane faster a boat at lower RPMS, with an under powered OB must go full hammer down.

Some data is needed :

-What's max HP, N? of passengers transom rated for ? How many boaters do you usually go boating with ?
-Which trim position was OB at when trying to plane ?
-Is it a manual or hydraulic trim ?
-Check if going full hammer down if combo planes faster on flat calm water cond.

You can better to some extend the overall combo performance with optimun OB/transom height along a prop maximization. Yams usually run 5000-5500 wot rpm range.

Happy Boating

 

[Adam Costa]

Sea rider,

Thank you for the response. You're correct, I was not articulating myself properly.
Max HP rating for the boat is 75, 6 passenger.

I usually boat with 2 people. 3 max. (including me)

Hydraulic trim.

Tried several trim positions while attempting to plane from a dead stop (full hammer down).

Would going with a pitch of 11 or 12 give me faster acceleration from a dead stop?

 

[Starcraft5834]

put a 4 blade prop on it.... more low end punch. best for heavy under powered boats.. like mine you will be surprised how effective they are. more blades= more thrust.. period.... they offer improved hole shot,, will lose about 1-3 mph top end....

 

[Adam Costa]

Imperial,

Thank you for your response. Recommend a diameter size/pitch?

Leaning towards

http://boatpropellers.iboats.com/Ya...-111-11_Propeller/399/8567/?cart_id=399077641

 

[b.gagnon]

A friend of mine has an 04 60hp Yamaha on a similar boat with a 14p prop and it has Nooooo power!
30MPH is great for that setup and lowering the pitch will loose speed.... Make life easy and get Trim Tabs....

 

[Adam Costa]

Thank you, B.gagnon!

 

[Sea Rider]

If with a 14 pitch OB is already revving 5300 wot rpm from max 5500 range, imagine with a 11-12 pitch, will achieve a superb hole shot as loaded while OB over revs at full throttle, and that's for sure. Now imagine solo boating at full throttle. Both of us are at the under powered OB kingdom. My boat is rated for max 7 passengers along max 50 HP-OB.

With a 18 HP-OB OB sitting at ideal transom height and a maximized one less prop pitch from factory delivered and 2 adults up OB revs happily to its max factory stated 5800 wot revs. Has outstanding hole shot, nice close dime turns at speed, while losing slight top end speed which doesn't matter to me. I'm way under powered with 2 up with a 18 HP than you with 3 up and a 60.

Can better the performance by optimizing OB height along a prop maximization. If possible, send current prop to a prop shop and have it repitched to say 13 from current 14. That way OB should rev around max 5500 wot range, can check that on a wot run with 3 up on flat calm waters. Maximizing less prop pitches while maintaining same 3 blades is a night/day boating difference.

Happy Boating

 

[Starcraft5834]

Imperial,

Thank you for your response. Recommend a diameter size/pitch?

Leaning towards

http://boatpropellers.iboats.com/Yam...****=399077641

I run Solas 4 blade.. you need to sort out pitch recommended based on WOT TAC recommended for your motor... if you are over limit on rpm a speck ease off the throttle... you just have to find best solution for your boat size and motor when normally loaded... 4 blade is my choice... those that run one also.. have never heard them say they wished they went back to a 3 blade. if your a speed enthusiast get a 3 blade and continue to struggle to get on plane.... 4 blade u will pop out of hole much quicker, stay on plane at reduced speeds and easier control at slower speeds.. you wont find many to dispute those characteristic facts of a 4 blade... (then again, some folks just like to argue) as they say, it is what it is.. good luck

 

[Sea Rider]

There are 2 alternatives :

Repitch current OEM prop from14 to 13 to pull wot revs up, including bettering hole shot or..

Buy a Solas 4 blade prop, If OB is already revving at 5200 wot rpm, with 4 blade 13 pitch should achieve same wot rpm. as with 3 blade prop, that's if the must go one less pitch reduction applies 100%

OB needs to rev towards max 5500 weot revs, a 12 will pull wot revs up, by how much ? impossible to tell, only possible on a wot run on calm water as usually loaded. You decide..

Happy Boating