Cruising Speed/RPMs with Universal 25XP

[sailscituate]

Looking for some insight/guidance on what we can expect under motor (acknowledging the variability of conditions). Generally speaking, we don't do a lot of motoring. We're on our first extended cruise and have run into unfavorable winds. I have a two-blade prop (not sure of the pitch) and have been maxing out at 4-4.3 knots. RPMs are at 2500, temperature a steady 160. We've got a long slog tomorrow with 8-10 mph winds forecast to be on the nose. Wondering if I just need to accept the fact that this is about as good as I'm going to get from the 25XP with my current prop configuration. Would also welcome thoughts on what I could expect by investing in a new prop.
Thanks in advance.

[Ken Juul]

M25xp with a 3 blade Michigan Sailor 5.5-6 depending on how heavy we are and wave conditions.

[mark_53]

M25XP 6.5 -7knots with a 3 blade 10 pitch prop. in protected water with no wind at 2500rpm.

[Stu Jackson]

M25 6.5 -7 knots with a 3 blade 15 x 10 pitch prop. in flat water with no/little wind at 2800rpm, clean bottom, 2500 rpm is 6+ knots.  WOT that I check regularly both in gear and out of gear is 3000.

My PO removed the two blade, so I don't know what that performance was nor do I recall the dia / pitch - it's somewhere at the bottom of my locker.

[Ron Hill]

As I recall the factory spec. 2 bladed prop is a 15" X 10". 

[sailscituate]

Thanks for the input. Obviously I'll be shopping for a 3 blade this winter. For the short term, any thoughts on running at 2800? I've pushed it on a few occasions, but haven't run that high for any significant time.

[KWKloeber]

Two questions - is your rpm accurate? Is your speed over ground accurate?

[sailscituate]

Yes on both fronts.

[Noah]

M25 6.5 -7 knots in flat water....with no/little wind at 2800rpm, clean bottom, 2500 rpm is 6+ knots.  WOT that I check regularly both in gear and out of gear is 3000.

I get approx same speed as Stu, on my 25XP but I have a 3-blade Flexofold—which I "hope" gives me more speed under sail than a fixed-bladed prop.

[KWKloeber]

Yes on both fronts.

speed how?

[Noah]

Less drag.

[Stu Jackson]

Thanks for the input. Obviously I'll be shopping for a 3 blade this winter. For the short term, any thoughts on running at 2800? I've pushed it on a few occasions, but haven't run that high for any significant time.

I ran at 2800 from SF to Maple Bay, British Columbia, in 2016, 1500 nm, 7.7 knots.  Don't "baby" the engine.  Still runnin'. 

I put a 3 inch HX on eons ago.

180F

[Phil Spicer]

   All of our racers down play the 3 bladed prop because of the drag, but it will back down right now. Wife does all of the motoring in and out of the dock. Some times I get a little worried if she comes in a little hot, but in 25 years she has always stopped well short of that steel sea wall. Fixed or folding, your choice. To me, I'll stay with 3 blades. (i don't race)

[britinusa]

Hey Guys,
would you go back and edit your posts in this thread and include the following:

Boat Name
#of Prop Blades
Max Engine RPM
Typical Temp at Max Engine RPM
Avg Speed at Max Engine RPM through the water.

I'm compiling a spreadsheet with averages that might help everyone.

Thanks.

Eximius:
3Blades
2100 RPM
152ºF (148ºF Thermostat)
6.5knots

Thanks.

Paul

[Ron Hill]

Guys : A while back I wrote a Mainsheet C34 Tech Note article on "Boat Speed; Prop and Engine"!!  You might find it interesting reading!!

A thought