I need to replace the propeller, shaft and stuffing box on the 27’ Hunter we recently purchased (we have some leaking problems with the rubber couplings, so this must be done ASAP). I am also in the process of looking for a rebuilt Yanmar engine (but haven’t found one yet). The current engine is a Renault and is frozen solid so it needs to come out when I replace the propeller, shaft & stuffing box. My question – is there a universal prop size –shaft, flange or adapter for the Yanmar that I can install? P.S. A BIG thank you to all who responded to our first question regarding hatch and motor replacement for this boat. We received a lot of valuable information and truly appreciate it. Thanks again!! Fair winds to all…and happy sailing! Thanks – Mark & Carol
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Engine before prop
Your prop diameter should leave a 25% clearance from the tip to the hull. I believe the original diameter was 12 inches, although I have seen 13 reported on this forum. Pitch depends on the power of the engine you get - the higher the HP, the higher the pitch. You should definitely wait until you have selected an engine before having a prop supplier run the numbers, and spec a prop for you. I don't remember the shaft diameter, but going with the same size you have is the right approach - is there something wrong with your shaft? If not, there is no reason not to re-use it. Check the archives for discussions on engines. A new, two cylinder 2GM20 Yanmar will fit into the h27 engine compartment. We ended up seeing the 1GM10 as a good step up from our blown 1SB8. We were very lucky to find a used 1GM10 with only 50 hours on it from Torreson! Give them a call, and you could get lucky. There is a guy who runs a marina near Bayfield, Wisconsin who is trying to corner the market on used/rebuilt Yanmars. He claims to have over 100 in stock - mostly awaiting rebuild. Sorry, I didn't keep his contact info! Once you decide on an engine, the shaft, fittings, and prop will follow. In Sandusky, our new stainless steel shaft was subbed to a local machine shop by our yard. At the prop shop's recommendation, we are running with our old prop to see how it works, but I expect to increase the pitch next winter, since the engines spins our 12/8 prop pretty easily. 12/11 is a diameter/pitch others have used. Good Luck! David Lady Lillie '77 h27
Your prop diameter should leave a 25% clearance from the tip to the hull. I believe the original diameter was 12 inches, although I have seen 13 reported on this forum. Pitch depends on the power of the engine you get - the higher the HP, the higher the pitch. You should definitely wait until you have selected an engine before having a prop supplier run the numbers, and spec a prop for you. I don't remember the shaft diameter, but going with the same size you have is the right approach - is there something wrong with your shaft? If not, there is no reason not to re-use it. Check the archives for discussions on engines. A new, two cylinder 2GM20 Yanmar will fit into the h27 engine compartment. We ended up seeing the 1GM10 as a good step up from our blown 1SB8. We were very lucky to find a used 1GM10 with only 50 hours on it from Torreson! Give them a call, and you could get lucky. There is a guy who runs a marina near Bayfield, Wisconsin who is trying to corner the market on used/rebuilt Yanmars. He claims to have over 100 in stock - mostly awaiting rebuild. Sorry, I didn't keep his contact info! Once you decide on an engine, the shaft, fittings, and prop will follow. In Sandusky, our new stainless steel shaft was subbed to a local machine shop by our yard. At the prop shop's recommendation, we are running with our old prop to see how it works, but I expect to increase the pitch next winter, since the engines spins our 12/8 prop pretty easily. 12/11 is a diameter/pitch others have used. Good Luck! David Lady Lillie '77 h27
Agreed, find motor first.
David's advice is right on. Everything could change based on your engine selection. When I replaced mine the newer engine was smaller and needed a longer shaft. And the shaft flange came with the engine. You can get ready by replacing the cutlass bearing in the strut. While you are at it check to see that it is securely bolted. You might want to rebed it with new stainless bolts and big fender washers. You could also be ready with a new stuffing box, new hose to connect it, and four new stainless clamps. Check the shaft log where the hose connects to make sure there are no thin spots or cracks from the old shaft wearing on it. Also be prepared to design engine mounts or add rails inside the current ones. My new engine was much narrower, I made custom mounts(Related Link). Is it any wonder a lot of sailors bolt on a motorboard for an outboard?
David's advice is right on. Everything could change based on your engine selection. When I replaced mine the newer engine was smaller and needed a longer shaft. And the shaft flange came with the engine. You can get ready by replacing the cutlass bearing in the strut. While you are at it check to see that it is securely bolted. You might want to rebed it with new stainless bolts and big fender washers. You could also be ready with a new stuffing box, new hose to connect it, and four new stainless clamps. Check the shaft log where the hose connects to make sure there are no thin spots or cracks from the old shaft wearing on it. Also be prepared to design engine mounts or add rails inside the current ones. My new engine was much narrower, I made custom mounts(Related Link). Is it any wonder a lot of sailors bolt on a motorboard for an outboard?
1980 shaft, etc.
Your efforts will be well worth it. 2 years ago, I replaced original engine (Westerbeke 10Two) on my 1984 H27 with a new Yanmar 2YM15, a 15 hp that meets the new Federal emissions standards. It did require one new galvanized steel rail since the new engine mounts were a little further appart on port side. Also watch your spacing between back of shaft flange and rubber prop shaft coupling. You must leave enough space to open stufing box to change stuffing in the future. The space is real close. Otherwise, installation was a breeze, I did mine while in the water, then later adjusted prop. Sorry, I don't remember prop size (next time I'm out, I'll look), but I agree with previous responce to have good prop shop do calculations. My shaft is a 3 blade and had prop shop adjust pitch. Good luck, Tony
Your efforts will be well worth it. 2 years ago, I replaced original engine (Westerbeke 10Two) on my 1984 H27 with a new Yanmar 2YM15, a 15 hp that meets the new Federal emissions standards. It did require one new galvanized steel rail since the new engine mounts were a little further appart on port side. Also watch your spacing between back of shaft flange and rubber prop shaft coupling. You must leave enough space to open stufing box to change stuffing in the future. The space is real close. Otherwise, installation was a breeze, I did mine while in the water, then later adjusted prop. Sorry, I don't remember prop size (next time I'm out, I'll look), but I agree with previous responce to have good prop shop do calculations. My shaft is a 3 blade and had prop shop adjust pitch. Good luck, Tony
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