Propellers - shallower pitch or reduced diameter? and Why?

[Terry]

Well Peter, the Honda will not accept a 14" diameter prop, too big, there is only 6.25" of clearance on the radius from the prop shaft to the anti-cavitation plate. I believe 12" diameter is your best fit and 3 X 12 X 10.5 would probably be ideal, likely what your Hustler is. I have two props the original installed by the dealer was a Hustler 3 X 10.75 X 11 or 12 can't remember but I do remember getting it re-pitched to 10.75 X 13. There is a shop in Richmond that does re-pitching. I get 57-5800 rpm from it but obviously it slips a fair bit. I also have a Solas Alcup that I also had re-pitched a bit, it is 4 X 11.4 X 9.75 and also puts me in the 5600- 5900 range depending on ballast. They both get me similar speeds as well but the 4 blade has better low speed control. I got the Solas at a sporting goods store just south of Belais Fair Mall in Wash. for about $185.00
One of the considerations I kept in mind was leaving a bit of room between the prop tip and the anti-cavitation plate to avoid unnecessary ventilation where the prop tip breaks through the water surface and pulls air down with it. Leaving a half inch clearance helps prevent some ventilation by keeping the prop lower in the water but you lose a bit of diameter in the process. I have had no problems with rpms @ WOT on both props but I do prefer the cruising speeds relative to rpms on the 4 blade Solas. I get about 10mph @ 3800rpm with it. Been a while to remember what I got with the Hustler but I may try it again this summer.

[beach]

I am investigating a new prop as well, and I would like to hear what other folks who sail above sea level have on their engines.

I have an 08 M with a Suz DF50, unaware what my current prop diameter and pitch are.

I sail on Ghost Lake Alberta which sits approximately 3000ft above sea level. I am told that the thinner air reduces engine output, and I find myself hitting 4400 max RPMs. any comments/ suggestions on what to look for and where to buy?

thanks!

[bscott]

You lose 3% hp/1,000' above sea level--your 50 is now 45 One rule is to reduce your pitch by 10% and hit your recommended max rpm. Do not reduce your prop diameter as you will reduce your manueverability--especially in reverse.
Check out www.powerthruster.com These work great for heavy boats with small diameter props.

Bob

[Crikey]

I'm running a Suzi DF60A with their three blade 12 X 11 - I think. I'll have to take a look again to be sure. I tried out both Propulse and Pirhana composites but the engine was too new and neither fit properly on the shaft, and were returned. Very disapointing! Spare blades and adjustability seemed the perfect way to go. I talked to a Propulse sales rep at the Toronto winter boat show (what else is there to do at this time of the year!) because they were now offering a four blade model but he still couldn't verify the fit for my model, and actually told me that I would wreck the bottom end with the increase torque requirements on a lower(?) hp engine. I remain convinced that was total BS!
My point is I still want to revisit the variable composites again - at least as a spare, and am wondering if anyone has had some experience they could relate, regardless of the outboard model?

Ross ......

[frede]

...Check out http://www.powerthruster.com These work great for heavy boats with small diameter props.

Bob

I would think if the Power Thruster really worked, at least one of the outboard manufacturers would be using them

[bscott]

Really works for me and several other board members as well--Merc BF 50/60 and 50/60 E-tec have HD lower units with 14" props designed for heavy semi-displacement boats. These engines cannot match the top speed of same hp engines with skinny lower units and 10/12" props. Big props have big lower units with more drag---so---since the light displacement boats/engines dominate the market and are less expensive, the OEMs don't have to add Power Thruster type devices because there is no demand---unless you have a light duty engine pushing a heavy semi-displacement, hard to maneuver, boat like a Mac.

Bob