20 SF Prop numbers

[FishStretcher]

I have to dig the prop out of the boat in storage this weekend. I was going to pull the tarp anyways. I will PM you with details. I actually only get as far south as Chelmsford regularly but I will be in Quincy Dorchester area the weekend after.

It is a $100 aluminum prop. I have some M gearcase props from a 175 kicking around, I think. 19" pitch. Let me look. I think that might be too big a gearcase.

[Old'sCool]

Pretty sure prop gods has an exchange program also

[McGillicuddy]

Chance yer numbers sound pretty good. The SCD prop is basically PT Props variant of the yamaha semi-cleaver. They come in 3 and 4 blade. pitch wise it sounds like you're where you wanna be. Semi cleavers like Stainless SCD are stern lifters. They will be a little thinner blade the your aluminum so it might have less drag therefore the 18p might get the last bit of throttle in play. They also have a 4 blade SCD that will give you more lift and control.

Another to consdider is the MQF series from PT Props. It a black max clone in stainless, has more blade area and is still the best stern-lifter. Also comes in 4 blade. SCD might give you more top end, the MQF maybe a little more economy at cruise. Both are easy to turn and very good for the SC. I often see SCDs on ebay for cheap.

Let us know about your results.

[CHANCE1234]

Finally got a chance to test out a new (to me) stainless steel prop. This one is a yamaha K18 3 blade stainless. Numbers below are trimmed all the way down

3400 RPM. 20 kts
4000. 24.2
4500. 27.8
5000. 30.5
5500. WOT 34

Trimmed up

3400. 20.3
4000. 25.1
4500. 28.5
5000. 31.5
WOT. Never wrote it down.

Overall I'm pretty happy with the numbers. At cruise looks like an increase of almost 2 knots which is fine by me.

[erebus]

So, same diameter as your original prop (13.25), but up 1 degree in pitch to 18 and SS instead of Aluminum?

Interesting.

I'd like to lower my cruise RPMS as well.
Not really concerned with top end. Maybe Ill swap the 13.25 17p aluminum I'm running on my 18sf (Merc 2 stroke 115) for an 18P SS as well.

[CHANCE1234]

It's a 13 diameter I believe. I usually cruise around 4k so I'm pretty happy with 24 knots or roughly 27 mph.