Question on Prop Size For 1979 F44 and Cruise Speed

[summer storm]

I love that boat! ah......... some day

[Lean Wolf]

Thank you! I love this boat too. Have loved it since the first time I saw it.

[Lean Wolf]

Thank you! I love this boat too. Have loved it since the first time I saw it.

[Peacock]

We have had our F44 for a year. When we bought it, the props were badly damaged. The original invoice from 1977 said it had 26x23,3 bladed props. We checked around and eventually settled on 24x24 cupped 4 blade props. The vessel runs just about 18 knots WOT at ~2100 rpm. I was told by the DD mechanic this WOT RPM was correct. Since then, our vessel has "gained" a bit of weight so I doubt it still runs that well. In the materials that came with our boat is an article on the F44 from YACHTING magazine, October 1977. The vessel had J&T GM 6-71 naturals, 310 HP each. The motors ran at 2500 RPM at WOT, turning 4 bladed 24x24 props through a 2:1 reduction. They reported 18 MPH at 2300 RPM and 21 MPH at WOT. I am glad to see another DD powered F44 on the list. The only other F44 owner I've met keeps his boat in Moline, IL. It is gas powered though as I think most of them were.

[Lean Wolf]

Peacock-Glad to see another F44 owner out there too. I appreciated the insight on the prop situation. Something is off with mine, it has the 24x24's and WOT is 2375 ad 2500 and I am only running 12 knots at WOT. When you say the props were cupped, did you have them tuned/set up that way or was it a stock prop you purchased?

[Peacock]

At the time, I was really concerned that the ruined props were not the 26x23 that the invoice from 1977 showed. I checked with several sources here in Florida and all agreed that 24x24, 4 bladed should be a good fit. The only ones I could find on short notice was the cupped pair. Most said that the light cup (one inch?) was equal to an inch of pitch and might take 100-150 RPM off the WOT. No problem. They seem to work well. I always thought that 24x24 was a bit anemic sounding for that size boat but what do I know. Is your bottom clean? I know you said the weight was 32000 pounds but that's the advertised weight. Have you had yours on the scales? When you pull for the season, maybe the lift can give you a true weight.

[Lean Wolf]

The bottom was cleaned recently and the speed was still slow when running it immediately after the bottom was cleaned. I need to pull the props off the boat and have them checked to make sure they are right and compare them to the set sitting in the engine compartment.

[JB]

I have a 1976 F44
I have Caterpillar 3208NA 210 HP Naturally aspirated diesel engines with 24 by 21 props and 2:1 transmissions. It reaches 2800 rpm
I am pretty sure your naturals are about 258 hp and redline at 2600. My guess is that assuming 2:1 transmissions (very likely) 24 by 24s would be original and ideal for your engines
JB
Apollo 1976 F44
Georgian Bay