I have a line on a Universal 8hp diesel, to replace my tired Atomic Four. My boat's a 37' full keeled yawl, will this engine have enough pop? If not, how muxh hp will I need?
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I wouldn't think so
I have 15 hp in a 34', 10,500 lb disp. fin keel'er and if I were to re-power I would go for minimum of 25hp. 8hp will move you around the marina but will be useless against any current or wind.
I have 15 hp in a 34', 10,500 lb disp. fin keel'er and if I were to re-power I would go for minimum of 25hp. 8hp will move you around the marina but will be useless against any current or wind.
Nope
I agree with David. I have a 18hp in my 33.5 and it's ok until the wind and chop are head-on, then she's underpowered.
I agree with David. I have a 18hp in my 33.5 and it's ok until the wind and chop are head-on, then she's underpowered.
Re-power
Eight horse power on a 37 full keel will help you dock in calm weather but not much more. I'm not an expert, but I would not go less than 20hp. I have a 30ft with 18hp and there are times more power would be nice. What size was the old engine?
Eight horse power on a 37 full keel will help you dock in calm weather but not much more. I'm not an expert, but I would not go less than 20hp. I have a 30ft with 18hp and there are times more power would be nice. What size was the old engine?
Look for more power
Our 27', 5200# boat was a little underpowered - but managed - when bucking the tides and current in the Navesink River with a 10 HP Yanmar diesel. You will need more when in difficult situations.
Our 27', 5200# boat was a little underpowered - but managed - when bucking the tides and current in the Navesink River with a 10 HP Yanmar diesel. You will need more when in difficult situations.
Displacement
I am not an expert either but I thought I read some where that 2 hp for every 1000 lbs of displacement is a good rule of thumb. My boat displaces nealy 12,000 lbs and the 27 HP diesel is plenty. Just my 2 Cents... John s/v Lady K
I am not an expert either but I thought I read some where that 2 hp for every 1000 lbs of displacement is a good rule of thumb. My boat displaces nealy 12,000 lbs and the 27 HP diesel is plenty. Just my 2 Cents... John s/v Lady K
Thank you, one and all!
I've said it before, and I'll say it again, as many times as anyone would like to hear it: This forum is the best! Thanks for the quick response. I thought that 8hp was too little, especially since I think my Atom Bomb is 28hp, but it's great to hear other opinions. I like that formula: hp/gwt, I'll use that in my search.
I've said it before, and I'll say it again, as many times as anyone would like to hear it: This forum is the best! Thanks for the quick response. I thought that 8hp was too little, especially since I think my Atom Bomb is 28hp, but it's great to hear other opinions. I like that formula: hp/gwt, I'll use that in my search.
Repower
Take a look at the vetus diesel, they make a wide range of small diesels and are half the weight of Yanmar. There is a guy in Holliston Mass that sells the for a real good price. I dont remember the name of the company but the phone number is 800 runs new ( I think)
Take a look at the vetus diesel, they make a wide range of small diesels and are half the weight of Yanmar. There is a guy in Holliston Mass that sells the for a real good price. I dont remember the name of the company but the phone number is 800 runs new ( I think)
That's not all
Prop size and pitch also need to be matched properly with an engine in order to provide the proper 'punch". Dave Gerr has a good chapter on this in one of his books. (I got it from the library and can't remember the title.) Keeping the old prop you've had with the new engine (which, if a diesel, might turn more slowly, for example) might not make the boat go as well as it used to.
Prop size and pitch also need to be matched properly with an engine in order to provide the proper 'punch". Dave Gerr has a good chapter on this in one of his books. (I got it from the library and can't remember the title.) Keeping the old prop you've had with the new engine (which, if a diesel, might turn more slowly, for example) might not make the boat go as well as it used to.
Rebuilt A4 is pretty cheap ......
A 'short block' Atomic Four from www.moyermarine.com will probably be the best value. They also sell total rebuilt 'long blocks' ... all you need is a new starter and ignition system. With an oil burner you will definitely need to change beds, fuel tank, prop and shaft, and the entire exhaust system, etc. .... all at significant extra hidden costs. Then expect the boat to sit quite differently on her lines due to the extreme weight difference. Don Moyer (Harrisburg Pa) is the world's reknown guru on the A4. He also has a shop in Chestertown so you wont have to travel that far to pick one up. Unless your A4 has corroded through, they hardly ever really 'wear-out'. A modernization of electronic ignition/electric fuel pump, and add on Fresh water cooling usuallly will restore a 'tired' old A4.
A 'short block' Atomic Four from www.moyermarine.com will probably be the best value. They also sell total rebuilt 'long blocks' ... all you need is a new starter and ignition system. With an oil burner you will definitely need to change beds, fuel tank, prop and shaft, and the entire exhaust system, etc. .... all at significant extra hidden costs. Then expect the boat to sit quite differently on her lines due to the extreme weight difference. Don Moyer (Harrisburg Pa) is the world's reknown guru on the A4. He also has a shop in Chestertown so you wont have to travel that far to pick one up. Unless your A4 has corroded through, they hardly ever really 'wear-out'. A modernization of electronic ignition/electric fuel pump, and add on Fresh water cooling usuallly will restore a 'tired' old A4.
I'm gonna second Rich's suggestion about
sticking with an A4. I have a 18HP diesel in a newer boat and like it but the Atomic was a classic that is pretty bulletproof when done right. Besides costs & all the work of changing fuel systems etc., if you do have to run the engine, (which most of us dislike) gas engines are quieter and smoother than oil burners.
sticking with an A4. I have a 18HP diesel in a newer boat and like it but the Atomic was a classic that is pretty bulletproof when done right. Besides costs & all the work of changing fuel systems etc., if you do have to run the engine, (which most of us dislike) gas engines are quieter and smoother than oil burners.
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