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12-06-2016, 08:42
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#1
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Registered User
Join Date: Aug 2012
Location: NS
Boat: Grampian 26
Posts: 26
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LOWER HORSE POWER
We have a Hunter Legend 37, 14,900# light ship, probably 17,000+ as is. Just blew the original Yanmar 3HM35F diesel (34 HP), have available a 30 HP Yanmar as replacement. I believe our prop is 16" x 10, two blade.
Anyone have experience or wisdom on a repower like this? Or are driving a boat of similar displacement with 30 HP?
Many thanks, Don
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12-06-2016, 08:55
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#2
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,483
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Re: LOWER HORSE POWER
Maybe compare the HP curves on the two engines. Some engines are rated HP at very high rpm, which really means it's not that HP to me......others not so much.... Depending on that it may work fine. My Hans Christian 38, a very heavy boat, had a 25 HP Yanmar in it. It was not enough really in a chop etc, but was in there for many years. It was an older Yanmar rated at a lower rpm though.
Which model is the 30 Hp yanmar you are considering?
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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12-06-2016, 11:03
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#3
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Senior Cruiser
Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 3,499
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Re: LOWER HORSE POWER
There's a 3HM35F on Ebay in Connecticut w/300 hours for $2000. No big alignment change, fuel, power, etc.
Yanmar Diesel Engine 3HM35F Used | eBay
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13-06-2016, 00:59
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#4
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Registered User
Join Date: Apr 2013
Posts: 11,002
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Re: LOWER HORSE POWER
How did the boat handle with the 34hp? Assuming it was plenty, you can probably get away with the small decrease in power to 30hp. If the 34hp was marginal, I wouldn't do it.
If you do it, set aside a little bit to have the option to change out the prop, if it can't get up to full RPM with the lower HP, a drop in the pitch to 8" or 9" will probably get you back the full RPM.
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13-06-2016, 03:53
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#5
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Registered User
Join Date: Oct 2011
Location: Fairhope, AL
Boat: Cabo Rico 45 build #005
Posts: 217
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Re: LOWER HORSE POWER
My portly Allied Seawind II weighs in more than 15,000 lbs and originally had a 25 horse W30. I have since replaced it with a Beta 30 which does fine, 16" prop as well.
Sent from my iPad using Cruisers Sailing Forum
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13-06-2016, 09:16
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#6
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Registered User
Join Date: Apr 2007
Location: Marina del Rey, California
Boat: President 43 Sportfish
Posts: 4,105
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Re: LOWER HORSE POWER
Quote:
Originally Posted by valhalla360
...set aside a little bit to have the option to change out the prop...
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No need to change it; just re-pitch.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
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13-06-2016, 09:54
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#7
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Registered User
Join Date: Sep 2009
Location: Houston
Boat: ‘01 Catana 401
Posts: 9,626
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Re: LOWER HORSE POWER
Quote:
Originally Posted by stevec195
My portly Allied Seawind II weighs in more than 15,000 lbs and originally had a 25 horse W30. I have since replaced it with a Beta 30 which does fine, 16" prop as well.
Sent from my iPad using Cruisers Sailing Forum
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Our also chunky allied seawind II with a Phasor 30 does quite well also (14,900 light, best guess now would be 16,000). With a 16"x10" prop we generally cruise at 1800-2200 rpm (max of 3000) and make 4.5-6 through the water depending on conditions. There is plenty of extra power beyond that.
Sent from my iPhone using Cruisers Sailing Forum
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13-06-2016, 10:22
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#8
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Registered User
Join Date: Aug 2012
Location: NS
Boat: Grampian 26
Posts: 26
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Re: LOWER HORSE POWER
Thanks to all who have replied, this forum is indeed a great resource!
Don
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13-06-2016, 11:28
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#9
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Registered User
Join Date: Jan 2009
Location: The Maritimes
Boat: 1980 CheoyLee35
Posts: 290
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Re: LOWER HORSE POWER
I repowered my CL35 with a 27 hp 3YM30 when I replaced a 40 hp Pathfinder. It would be about the same displacement as your boat and I find it has worked well. I did talk to Bob Perry before making the change and he was confident it would do the job.
Good luck with the changeover!
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13-06-2016, 14:36
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#10
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Registered User
Join Date: Aug 2012
Location: NS
Boat: Grampian 26
Posts: 26
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Re: LOWER HORSE POWER
Thanks, we'll go with the 30 HP Yanmar and report how it does. If the mechanic will certify it will turn up to rating & compression proves good.
Thanks again, Don
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