Just joined the forum, where I’ve already gleaned a lot of good info by “lurking” over the years.
I own a Freedom 44H currently undergoing an extensive re-build.
The original Perkins 4108 is toast, so will need replacing. They were originally rated at 50hp but from what I’ve read online, only really put out about 30-40hp, especially the older they get. While good engines (I’ve had several), they are bit ancient at this point so rather than rebuilding a dinosaur I’m considering a re-power with something more recent, like a Yanmar, Volvo-Penta or Beta.
Questions for you F44H owners out there:
Do you feel the original engine had enough power, or that she’d need more or could get away with less?
(Normally I’d choose a bit more power than actually needed and then operate at less than 100%, but I have never operated this particular boat model under power, hence the question).
If you have re-powered a F44H, what did you install and what’s your views/opinions after the switch?
I own F44 centerboard model with original Yanmar 4JH-TBE 4 cyl. 55hp at 3600 rpm max (50 at 3500 ) turbo diesel. ~38 hp at 2700-2800 rpms in cruising mode. Original 8.8’’ X 19’’ max-prop, orig. gear box had 2.61:1 ratio. At some point in time PO replaced transmission with new one , 2.17:1 forward reduction ratio so engine did not rev up higher than 2000 rpm when I bought her. It corresponds to approx. 27 hp. (from yamnar specs chart ). I could get about 5.5 – 5.6 kt speed in calm waters. And about 4-4.5 kts heading into wind (this hull creates a lot of windage) I’ve reduced the pitch to 6.3’’ the following season so engine began to rev up to about 3000+ rpms with slight reduction in max speed (pitch was too small ) and sent my prop for rebuilt this year , they cut blade tips to 17’’ prop diameter.
if max hull speed (8.4 kts) is not that important so probably you can get away with less powerful engine.
The boat is heavy , about 25000 lbs and doesn’t turn well in narrow places, doesn’t back up strait either, has prop walk … so I feel that engine is kind of important in crowded spaces (unless you got full coverage )and I would stick with the original one, specially that Perkins are low rev engines vs. Yanmars. You can’t install prop bigger than 19’’. In my case blade tips almost touched the hull … and if you play with some prop pitch calculation applications then It looks like 50-55 hp is the optimal power range for that particular hull / weight combination. There were different engines installed on F44 (Yanmar, Perkins , Vetus), all in range of 50 to 60 hp , 17’’ props
Thanks for your extensive reply and sorry for the late reply - busy days, tight lines!
Sounds like sticking with whatever Volvo/Yanmar/Beta/Perkins engine I can find used/rebuilt in the 50hp range is the way to go.
BR
Mats
Speaking of max-prop. I sent my 19’’ prop for refurbishing over this winter to PYI. (b.t.w. it was not that expensive, about $500 ) Called them up , they suggested to cut the blades to 17’‘. I asked what if wanted to go back to original 19’’ prop diameter and was told that they could weld blade tips back up to 19’’ again ?? … anyway I got 17’’ max-prop with 10.4 pitch now (2.17 gearbox ratio). Settings seem to be right spot on. They cut blades , polished prop, replaced cone gear inside the hub. Seems that vibration is goned too.
Thanks for the update!
There’s a 3-blade 17" Maxprop on ebay currently for a 1 1/4" shaft, maybe I should get it although it looks quite ancient.
Don’t know my shaft dia. but need to replace it anyway - what is the shaft dia. on your F44 c/b?
I see that they now charge for access. Too bad, it’s a great article, but I would think that it would be worth paying for.
Anyhow, the article discusses how to determine optimal prop size and pitch based upon engine characteristics. One of the things that I learned from this was that the prop on my 40/40 is too large because the prop tip speed is too high at the optimal engine RPM. These all tie together and it’s fairly clear to me that Freedom didn’t understand the mathematics behind optimal prop sizing.
These all tie together and it’s fairly clear to me that Freedom didn’t understand the mathematics behind optimal prop sizing.
Yes, I asked myself the same question. I got some old surveys / documentation with my boat and reading them concluded that 19’’ max- prop has been originally installed by the factory. According to the surveys my lugging yanmar always suffered from oversized prop, even with 2.64 gear ratio.
I also recall reading this article referred by Geoff in one of his posts , interestingly enough I noticed 2 kinds of vibrations in the shaft: one was kind of acute , constant after 1500 rpm, slightly increasing with rpms and the other one is king of “wobbly” after 2500 rpms which exactly coincided with 95 ft / sec blade tips speed of my orig. 19’’ prop. I can’t say for sure if that was cavitation … but cutting prop to 17’’ diam. definetly helped
Don’t know my shaft dia. but need to replace it anyway - what is the shaft dia. on your F44 c/b?
I also replaced the shaft / cutless bearing . I noticed that my shaft has been slightly worn on one side in area of contact with cutless bearing , probably from misbalance in max-prop. While checking around for the new shaft or repair my old shaft found again that price range is quite drastic … from $400 to $1500 and seems to be not justified by any means… eventually I found a place called ‘properpitch’ in Delaware. I do not have any affiliation with them. They seems to be quite knowledgeable and friendly , best price, prompt shipping . They have website , price list …e.t.c. I can recommend them highly.
That is what I found out as well. Mostly there are two types alloys for prop shafts on the market: alloy 22 and alloy 19 . A22 is almost twice more expensive with marginally better material properties. Talking with these guys I understood that for my particular 1 ¼ ‘’ shaft it is just no matter if it A22 or A19 while all the other shops simply insisted on A22 only…
Hi
I am a bit late into the discussiuon, but the weather in the UK has been too fabulous to read blogs and not go sailing.
I replaced my Perkins 4108 2 years ago on my F44 with a Beta 50hp and a new gearbox. It drives a maxprop. I get a cruising 6kts at about 1800 rpm. Fuel consumption about 3litres per hour… Wonderful engine based on a Kabuta block. Reasonably quiet with useful prop wash. I added a monster second alternator dedicated for the house batteries.
I regret not doing this long ago as I have been chucking good money after bad on the old engine.
Richard
Hi RIchard, thanks for your input!
Have been looking at the Beta 50 myself, good engine and company.
What gear ratio, size max-prop (2 or3 blade?) and pitch do you have?
Cheers,
Mats
Sorry for the delay : Been sailing! I have a F44 cat ketch which i bought in Maine in 1999. I presume this the same as a F44H but whatever, i dont think it will make much difference to my experience.
I replaced the perkins 4108 with a perkins 4107 in 2000 in USA which was a mistake. It was a very old fashioned engine based on pre war Bedford truck and therefore noisy but reliable.
In 2010 I bit the bullet and replaced it with a Beta 50hp which is based on a kabuto block. The transformation was incredible. I have a maxprop and at 1800 revs in flat conditions i achieve 6 knts using 3 litres per hour. I wished I had been braver and sorted it earlier.
I dont think a bigger engine would achieve that much, as at full blast, the stern digs in and you only go marginally faster.
Putting it in was interesting as it was all a bit further forward and required some alterations to the carpentry but quite acceptable.
My only regret is that we didnt choose the shallow sump option as this would have made the fitting a lot easier.
Richard Franklin