Hey Gang, The last time I wrote about my old diesel compression I learned about compression and also learned about trimming Spinakers. I have decided to replace my old 3MGF 20 hp diesel on my Hunter 34 with a new engine. Never mind the lecture about the sleeves and how easy it is to rebuild, I decided to treat myself to a new engine. The original diesel was 20 HP the new 3YM series comes in both 20 and 30 hp. Which engine do you recommend and why? This is a test, and for extra credit would you change the prop size, if yes to what size? Charlie
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not sure you are buying much
My old 3GMF still drives the boat at 6.5-7 knots. That is about all it will do unless you can figure a way to get that 5000 pound keel to get up and let the hull plane!! I suspect your limiting factor in prop dia will be tip clearance. Not sure what this is buying you?
My old 3GMF still drives the boat at 6.5-7 knots. That is about all it will do unless you can figure a way to get that 5000 pound keel to get up and let the hull plane!! I suspect your limiting factor in prop dia will be tip clearance. Not sure what this is buying you?
Tihs is a great question...
Everyone knows of my buisness, so I throw in my $.02. Don't limit your self to Yanmars new offerings! The new engines actualy use older designs to accomplish the same goals. When I saw the new YM series I thought Yanmar took a step backwards. Don't get me wrong I love the GM and JH series and think their some of the best engines around. Universal and Beta both use a Kubota base engine amd marinze it. The Kubota is lighter and smother. Look at the Universal 25XPB and if you want reserve power look at the M35. I have a diferent philosiphy on hp sizing for a crusing yacht. Since a hp rating is at maximum continous and the hp climps to this number as the RPM's increase. I like to size an engine on hull needs at cruise RPM. This works out to give you extra power for emergencies. Another thing you gain is extra power to run larger alternators/fridge compressors or watermaker pumps. Remember it takes 10hp to run a 100 amp alternator. On an H34 I'd go for 30-35hp and prop for hull speed at max cruise RPM, some where around 3000 RPM. E-mail me off line if you have more questions. Here are some links for you; www.westerbeke.com www.betamarinenc.com Pat McCartin Inland Marine Diesel Buford, GA imd_ga@hotmail.com Member A.B.Y.C.
Everyone knows of my buisness, so I throw in my $.02. Don't limit your self to Yanmars new offerings! The new engines actualy use older designs to accomplish the same goals. When I saw the new YM series I thought Yanmar took a step backwards. Don't get me wrong I love the GM and JH series and think their some of the best engines around. Universal and Beta both use a Kubota base engine amd marinze it. The Kubota is lighter and smother. Look at the Universal 25XPB and if you want reserve power look at the M35. I have a diferent philosiphy on hp sizing for a crusing yacht. Since a hp rating is at maximum continous and the hp climps to this number as the RPM's increase. I like to size an engine on hull needs at cruise RPM. This works out to give you extra power for emergencies. Another thing you gain is extra power to run larger alternators/fridge compressors or watermaker pumps. Remember it takes 10hp to run a 100 amp alternator. On an H34 I'd go for 30-35hp and prop for hull speed at max cruise RPM, some where around 3000 RPM. E-mail me off line if you have more questions. Here are some links for you; www.westerbeke.com www.betamarinenc.com Pat McCartin Inland Marine Diesel Buford, GA imd_ga@hotmail.com Member A.B.Y.C.
Charlie, did you get my email?
It's the one signed by a guy named Fred. Don't confuse it with what Pat wrote, even though it's nearly word for word.
As far as 'horsepower' that is.
It's the one signed by a guy named Fred. Don't confuse it with what Pat wrote, even though it's nearly word for word.
As far as 'horsepower' that is.
I just replaced with a 3YM30
I just got a 37C last October that had a blown Yanmar (3 in hole where the rod took an exit). I repowered with the 3YM30. It is an amazing little engine. It runs smooth, quiet and strong. It's paired up with a 16x10 3 bladed prop (I don't intend to race). At 2600-2800 rpm it pushes my 37C at about 6.5 and has the transom buried about 2 inches. Trust me I've got lots of throttle left, as I can "gun-it" up to close to 4000 rpm for very short bursts. I had mine installed by List Marine in Sausalito, CA. All said and done with new shaft, stern tube, drip-less packing bearing, strut, and prop it was around $15k to $16k. Everything from the front of the engine to the stern tip of the shaft is new. The only thing we saved was the controls and some of the exhaust system. The engine starts like a car, and I was told that unless I'm in Polar Regions I should never have to use the glow plug. It's efficient and uses about 2 quarts of fuel per hour at cruising speed. My 44 gallon tank should give me a theoretical range of approximately 500 NM.
I just got a 37C last October that had a blown Yanmar (3 in hole where the rod took an exit). I repowered with the 3YM30. It is an amazing little engine. It runs smooth, quiet and strong. It's paired up with a 16x10 3 bladed prop (I don't intend to race). At 2600-2800 rpm it pushes my 37C at about 6.5 and has the transom buried about 2 inches. Trust me I've got lots of throttle left, as I can "gun-it" up to close to 4000 rpm for very short bursts. I had mine installed by List Marine in Sausalito, CA. All said and done with new shaft, stern tube, drip-less packing bearing, strut, and prop it was around $15k to $16k. Everything from the front of the engine to the stern tip of the shaft is new. The only thing we saved was the controls and some of the exhaust system. The engine starts like a car, and I was told that unless I'm in Polar Regions I should never have to use the glow plug. It's efficient and uses about 2 quarts of fuel per hour at cruising speed. My 44 gallon tank should give me a theoretical range of approximately 500 NM.
don't change the prop
you should not have to change the prop unless you change the transmission ratio. Both engines (or any other mfg engine) should tack out at the same rpm range. So unless you change the ratio of the trans the shaft will still be turning the same speed at the same rpm's. If you change the trans ratio go to a good prop shop to run the numbers for you new engine and trans set up. The same would be true if your old engine and new engine have different operating rpm ranges.If it were my boat I would put in the 30 hp just because I would want the extra hp. unless it means changeing the engine mount set up.Your repower job should give you the same performance as before. This all assumes you were satisfied with the set up before the engine went bad.
you should not have to change the prop unless you change the transmission ratio. Both engines (or any other mfg engine) should tack out at the same rpm range. So unless you change the ratio of the trans the shaft will still be turning the same speed at the same rpm's. If you change the trans ratio go to a good prop shop to run the numbers for you new engine and trans set up. The same would be true if your old engine and new engine have different operating rpm ranges.If it were my boat I would put in the 30 hp just because I would want the extra hp. unless it means changeing the engine mount set up.Your repower job should give you the same performance as before. This all assumes you were satisfied with the set up before the engine went bad.
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