I've got a Cape Dory 28 Open Fisherman with a 275hp Chrysler V8,
that I love, but I'd like to get more speed out of her. Has anyone successfully upgraded to a higher horsepower gas V8, and what can I expect for a cruising / top speed?
Thanks.
Cape Dory 28 Repower
Moderator: bobdugan
-
alfin32
- Posts: 7
- Joined: Mar 29th, '08, 11:17
- Location: '87 Cape Dory Open Fisherman
"Barchetta"
Marblehead, Ma.
Dave,DaveCD28 wrote:I don't know alot about the Cape Dory 28 power boats, but if it is a displacement hull don't expect much of an improvement, unless your current engine isn't pushing it to hull speed or you are referring to better performance when you are heading into big chop and wind.
On a displacement hull, the hull speed is about the max you can expect no matter what reasonable engine you have.
Thanks, it is a full displacement hull, but a lot of the original literature quotes a 16-17kt. cruise, and 20kt. top end. I'm more in the 10-12kt. cruise, and 15kt. top end. Is this the best I can expect?
While I have no experience with the specific boat, the same basic rules apply to all boats. Yes, you can make your boat faster with more power but it won't be a lot faster. If you are seriously considering a repower, I would strongly suggest looking at switching to a diesel. I would be happy to talk to you about the reason that I make this suggestion if you would like.
The drive system of a boat is just that, it is a system. The important parts are the hull shape and associated displacement, the engine, the gearing and the propeller. Before considering a repower, I would try to see if the current system is optimized. The end goal is to allow the engine to hit its governed rpm while putting the maximum amount of load on it. If you have too much gearing/prop, you will not be able to go very fast not for lack of power but for lack of rpm. If your gearing/prop is too tall, your engine will be lugging and you won't go very fast since you won't be able to get the rpm up. This is a much easier condition to notice than the other way around since you won't be able to hit the governed rpm.
This is very general but hopefully it helps you to think of the relationship between the engine powerband, your gearing and your prop pitch.
The drive system of a boat is just that, it is a system. The important parts are the hull shape and associated displacement, the engine, the gearing and the propeller. Before considering a repower, I would try to see if the current system is optimized. The end goal is to allow the engine to hit its governed rpm while putting the maximum amount of load on it. If you have too much gearing/prop, you will not be able to go very fast not for lack of power but for lack of rpm. If your gearing/prop is too tall, your engine will be lugging and you won't go very fast since you won't be able to get the rpm up. This is a much easier condition to notice than the other way around since you won't be able to hit the governed rpm.
This is very general but hopefully it helps you to think of the relationship between the engine powerband, your gearing and your prop pitch.
-
DaveCD28
- Posts: 86
- Joined: Aug 7th, '09, 14:21
- Location: 1978 Cape Dory 28 #174, Sanuye, Melbourne, Florida
There is a website for cape dory power yachts at www.capedory28.info
They have some threads in their forum on repowering.
This site has mainly sailboat owners so you might not find people experienced with the power yachts here.
They have some threads in their forum on repowering.
This site has mainly sailboat owners so you might not find people experienced with the power yachts here.