Found out why...

[Swamp_Bear]

My boat had a GREAT hole shot, but I never could reach maximum RPM. Top speed seemed to level off in the low 30's (by GPS), while others here were reporting speeds near or over 40.

Suspicions were confirmed this weekend when I took the boat in to a different Triumph dealer than the one from which I had bought it. It had a 19 pitch prop on the Yammy 150, but apparently it should have been a 17. No matter, I'm upgrading to stainless anyway, so the hole shot hero will make an excellent spare.

Should I stick with three blades rather than four? Sometimes I host friends who like to ski, and I'd hate to loose my ability to yank them up right quick.

[rudderhinge]

Swamp Bear, what was the diameter of the prop that you have been using?
I am using a Stiletto 14 1/4"X17" on my 215 with a F-150 Yamaha. My boat will get on plane in 2 1/2 to 3 seconds with a full tank of gas, all the gear used for fishing and 250 pounds of me with out using the trim tabs. My top speed is 43-44 mph at 5900-6000 RPM. I can cruse at 30 MPH, at 4000 RPM, and use around 5.5 gallons of gas an hour.
A four blade prop will give you a better hole shot than a three but you will lose some top end speed.
I have not pulled a skier so im not sure how much this help you. I do know your gas consumption will get better (less) by going to a 17" pitch prop. Good luck selecting you prop. Sometimes it just takes a little magic to get the right prop. Bob

[Mark Marcoux]

I also have a 19 pitch and was recently told It needs to be a 17. I can reach 43 mph however my holeshot is not there, I'm surprized to here that you are happy with yours. The mechanic was surprized to here I could reach that speed but he really noticed how much of a dud it was out of the hole. My max RPM is 5200 at full trim and that will give me 43 mph by the boats speedo and the GPS shows 37-38 kts. I'll be getting a 17 in the near future also. Please keep me informed of your performance changes.

[Swamp_Bear]

Thanks for the responses. I don't know my existing prop's diameter, and now that it's at the dealer, I can't measure it.

I would have thought that a prop with a higher pitch would allow me to cruise at lower RPM, and thus use less gass (kind of like overdrive on a car). But I guess gear ratio doesn't translate to prop pitch quite the same way.

I'm still not sure about the three vs. four blades though. I tend to cruise at around 22 mph, not WOT, so getting more top end isn't quite as important to me as general performance and efficiency - and pulling power, of course.

[Putershark]

Then either a 4 or 5 blade is the way to go. Might loose a knot or 2 of top end, but it will launch much better and run smoother at cruise since with a 4 blade (most common) always has the same number of blades hitting the water or going up all at the same time.

[Swamp_Bear]

Thanks, Putershark. I don't mind missing 1 or 2 knots off the top if it gets me on plane faster and rides smoother.

[ILLOGICAL GGC]

bear
the 19" is great for cruising and will get the best mpg ,however you will not get to the max rpms of the engine nor will you get out of the hole to pull anybody . That being said ,the 17" should get you close to the yami wot rpms and and you should jump up on plane pronto. i also had the same stilleto as rudderhinge on a 186 bay with yami 115 4s and it was a great all around prop for that boat.
i currently use a propulse adjustable pitch on my 140 4s johnson on a 210cc and i can go from overrev at 16",to 6200rpms at 17 "for skiing and nasty inlets,to 6000rpms at 18" for best all around performance and 5600rpms at 20" when cruising in protected waters and no hurry to get there. i turn higher rpms because the prop is composite and it doesnt take as much power to turn it.

i find this easier than owning 3 different props as i actually do these 3 different styles of boating

hope this helps a tad
Berto