this 5 blade 21pitch give anymore speed than my 19pitch 3 blade?

[weider1717]

I have a 19ft ski boat with an MR 1.50 drive and a GM 350 260hp engine.

engine WOT is doing 5,000 rpm which is a bit much so been looking on ebay for a 21pitch prop to replace the 19pitch.

question is will this 5 blade 21 pitch lower my rpm's and give me that little bit more speed a 21 pitch should while giving me great hole shot. I just look for a 3 blade 21 pitch?
http://cgi.ebay.com/ebaymotors/MERC...9990460QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

 

[Philster]

Re: this 5 blade 21pitch give anymore speed than my 19pitch 3 blade?

Going up in blade count is going to knock RPMs down. The extra blades are extra resistance, and extra bite. So, going up in blade count gives you better hole shot results from the good bite, but the extra resistance of the blades knocks some RPMs off the top end. You might enjoy mid-range more with a 4 or 5 blader.

So, going up in pitch AND jumping up in blade count like that would probably knock off too many RPM.

You seem to need the same pitch and a 4-blade prop. You will like the hole shot, and you will knock off some RPM, but not too much.

 

[kartman]

Re: this 5 blade 21pitch give anymore speed than my 19pitch 3 blade?

you have got to take into account the size of the blade, and the diameter of the prop. if its a high 5, it will be a smaller diameter than a 3 or 4 blade prop. alowing you to run a higher pitch, and still maintaining your holeshot. if you do alot of towing with your boat, i would go with a high 5. right now i have a 21p on the same drive you do, and it works out great. but the only way to know for sure is to try a few new props.

 

[fossill]

Re: this 5 blade 21pitch give anymore speed than my 19pitch 3 blade?

A 4 blade Stiletto Bay Pro II gives a great holeshot as well as not losing too much in the top end. That would be my choice prop. 4 blades are apparently more efficient than 5 blades.