Freedom 44H Engine big enough/too big?

Engines, Drive trains, Propellers, Steering, Ground Tackle and other mechanical system
Matso
Posts: 7
Joined: Wed Apr 24, 2013 9:35 am

Freedom 44H Engine big enough/too big?

Post by Matso »

Hello all,

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:

1. 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).

2. If you have re-powered a F44H, what did you install and what's your views/opinions after the switch?

Best regards,

Mats

rds
Posts: 50
Joined: Mon Jul 06, 2009 9:32 pm

Re: Freedom 44H Engine big enough/too big?

Post by rds »

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

Matso
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Joined: Wed Apr 24, 2013 9:35 am

Re: Freedom 44H Engine big enough/too big?

Post by Matso »

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

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GeoffSchultz
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Re: Freedom 44H Engine big enough/too big?

Post by GeoffSchultz »

I would suggest that you read the following article:

http://www.morganscloud.com/2011/04/15/ ... propeller/

-- Geoff
BlueJacket
1997 Freedom 40/40
http://www.GeoffSchultz.org

Matso
Posts: 7
Joined: Wed Apr 24, 2013 9:35 am

Re: Freedom 44H Engine big enough/too big?

Post by Matso »

Thanks Geoff - the link goes to a feathering prop discussion - not sure how that relates to my engine query. Very interesting site, nevertheless!

rds
Posts: 50
Joined: Mon Jul 06, 2009 9:32 pm

Re: Freedom 44H Engine big enough/too big?

Post by rds »

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.

Matso
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Joined: Wed Apr 24, 2013 9:35 am

Re: Freedom 44H Engine big enough/too big?

Post by Matso »

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?

rds
Posts: 50
Joined: Mon Jul 06, 2009 9:32 pm

Re: Freedom 44H Engine big enough/too big?

Post by rds »

the same diameter, 1 1/4

Matso
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Re: Freedom 44H Engine big enough/too big?

Post by Matso »

Thanks!

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GeoffSchultz
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Re: Freedom 44H Engine big enough/too big?

Post by GeoffSchultz »

Matso wrote:Thanks Geoff - the link goes to a feathering prop discussion - not sure how that relates to my engine query. Very interesting site, nevertheless!
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.

-- Geoff
BlueJacket
1997 Freedom 40/40
http://www.GeoffSchultz.org

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