We bought our Hunter 33 this spring and we are generally happy with the boat. One month after we had our boat, the drive coupling separated between the Yanmar engine and the propeller shaft. It was quite a surprise and we were lucky that it happened when we had a lot of sea room to allow us to put the bolts back in again. The Hunter manual's recommendation said "routine inspection of the drive coupling bolts is a must". I asked Hunter to be more specific. Should we be doing it annually, monthly, weekly, daily, or should we stop the boat every hour and check it??? The local dealer service recommendation is that we should check it every time we go out. I had a chance to talk to the Hunter factory people last week and they said the Yanmar recommendation is to check it every 50 hours of engine use. Frankly, I am not sure if they relaxed it from every time we go out to 50 hours because it sounded so rediculous or whether they really have good technical information on the 50 hours. I am not sure whether to believe them because it is our life and safety that is at stake. My point to Hunter is that even though this is a tough coupling application with axial and shock loads, they should do better. I don't know of any outboard motor owner that check their propeller lock nut every time they go out or ever and they have the retaining nut in the water and rotating out when in reverse. The auto companies would not dream of asking their car buyers to check their wheel nuts everytime they go out in their cars. I wanted to put some slotted or castle nuts in instead of the regular nuts so that I can wire the nuts to prevent them from unscrewing from the bolt. This is already done with the set screw that holds the half coupling on to the propeller shaft. However, this is not possible because the output shaft of the Yanmar gearbox is so short that there is no clearence for a nut that is a quarter inch longer than the standard one. As it is, putting in a lock washer already resulted in rubbing the rim of the engine drip tray down. The other option is to drill through the nut and bolt and wire through but I can't get the drill in there because of a wiring pipe directly over the coupling blocking access. The factory response is that this is a Yanmar problem. They are sympathatic but I do not get the idea that I will be getting much more help from them on this issue. Are there any other Hunter owners that have this problem? Do you all check your drive couplings religiously? It is a scarry feeling when you expect the engine to work and it doesn't! Think about it next time you are in the marina or fighting the tides or in a storm. Can you count on your drive coupling to stay together? Thanks, Oliver.
Drive coupling for Hunter 33
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My take on it is that 50 hours is extra cautious. I don't think there is a real difference in couplings regardless of manufacturer. I have heard of them seperating or breaking on Cals, Tayanas, Passports and a couple of Hunters on this site. Most of the failures are them just losening up, but one broke. I think the close clearance you describe is typical. IMHO, I think new or just overhauled is when I get my failures and it may just have to do with stuff losening up a bit. You might consider lock nuts for piece of mind. Other than that, I'd inspect it every engine service. I'm inclinded to think this is a one-time deal. Of course, you may elect to do it more until you're again comfortable you won't lose your coupling. Good luck, RD
My take on it is that 50 hours is extra cautious. I don't think there is a real difference in couplings regardless of manufacturer. I have heard of them seperating or breaking on Cals, Tayanas, Passports and a couple of Hunters on this site. Most of the failures are them just losening up, but one broke. I think the close clearance you describe is typical. IMHO, I think new or just overhauled is when I get my failures and it may just have to do with stuff losening up a bit. You might consider lock nuts for piece of mind. Other than that, I'd inspect it every engine service. I'm inclinded to think this is a one-time deal. Of course, you may elect to do it more until you're again comfortable you won't lose your coupling. Good luck, RD
If you haven't noticed, It,'s a boat, not a car
Your Hunter 33, just like mine and every other boat built in the last 150 years or so, with the possible exception of a few Herreshoffs many years ago are made up of a hull and deck and an amalgam of bits and pieces from numerous makers all over the place. If you had enough catalogues and a set of molds you too could be a boat builder. To say that there's anything wrong with the coupling that has been used very successfully for many decades on tens of thousands of boats is ridiculous. You'd do a lot better looking at who last worked on the engine alignment to see who forgot to properly tighten the bolts. If you're that worried about it, take a hammer and cold chisel, ding the nut up against the threads of the bolt. If you want to get realy slick, go to a motorcycle shop and get tab washers to fit under the nuts and bend over. Wiring in the way? MOVE THE DAMNED WIRE! It's no excuse. It's your boat, you're the "Captain, it's your responsibility. Don't blame someone else. For the record, mine has never loosened, and I don't expect it to. PS: 50 hours is another way of saying once a season. This is just part of normal recurrent maintenance.
Your Hunter 33, just like mine and every other boat built in the last 150 years or so, with the possible exception of a few Herreshoffs many years ago are made up of a hull and deck and an amalgam of bits and pieces from numerous makers all over the place. If you had enough catalogues and a set of molds you too could be a boat builder. To say that there's anything wrong with the coupling that has been used very successfully for many decades on tens of thousands of boats is ridiculous. You'd do a lot better looking at who last worked on the engine alignment to see who forgot to properly tighten the bolts. If you're that worried about it, take a hammer and cold chisel, ding the nut up against the threads of the bolt. If you want to get realy slick, go to a motorcycle shop and get tab washers to fit under the nuts and bend over. Wiring in the way? MOVE THE DAMNED WIRE! It's no excuse. It's your boat, you're the "Captain, it's your responsibility. Don't blame someone else. For the record, mine has never loosened, and I don't expect it to. PS: 50 hours is another way of saying once a season. This is just part of normal recurrent maintenance.
Lawyers.
The response the company gave you sounds like was prepared for the tech guys by a lawyer. In todays world of "sue 'em" mentality the company is just trying to cover it's butt. Actually read your car owners manual closely, they do recommend you check your oil, belts, tire pressure and lug nuts very frequently. A big sticker on one of my utility trailer's says "check lug nuts every 50 miles", yeah right. Two suggestions. Many 'experts' recommend installing a shaft zinc INSIDE the hull, between the engine coupling and the stuffing box. Now if the bolts came loose, you'd lose power, but the shaft wouldn't back out and let the sea in. The other suggestion would be apply lock tite, but that would make future removal much harder. Living up north, we pull the boat each winter, so I do the zinc thing and check everything over the winter. G'luck
The response the company gave you sounds like was prepared for the tech guys by a lawyer. In todays world of "sue 'em" mentality the company is just trying to cover it's butt. Actually read your car owners manual closely, they do recommend you check your oil, belts, tire pressure and lug nuts very frequently. A big sticker on one of my utility trailer's says "check lug nuts every 50 miles", yeah right. Two suggestions. Many 'experts' recommend installing a shaft zinc INSIDE the hull, between the engine coupling and the stuffing box. Now if the bolts came loose, you'd lose power, but the shaft wouldn't back out and let the sea in. The other suggestion would be apply lock tite, but that would make future removal much harder. Living up north, we pull the boat each winter, so I do the zinc thing and check everything over the winter. G'luck
locktite?
I use the lock nuts that have a nylon insert, but I gather you do not have room for them. My next choice would be to put locktite on the threads. I've never had this problem with the coupler bolts, but I have had a lot of problem with the coupler to shaft connection working loose. With this, if it's been off I start by checking it after a couple hours, tightening it each time. Then, once a day, check and tighten. After I've gone several days with the bolts not moving when I try to tighten them, I go to once a week or so. Then I forget them. Since doing this, I've not had another work loose. I lost 2 before going through this routine. Gene Gruender Rainbow Chaser
I use the lock nuts that have a nylon insert, but I gather you do not have room for them. My next choice would be to put locktite on the threads. I've never had this problem with the coupler bolts, but I have had a lot of problem with the coupler to shaft connection working loose. With this, if it's been off I start by checking it after a couple hours, tightening it each time. Then, once a day, check and tighten. After I've gone several days with the bolts not moving when I try to tighten them, I go to once a week or so. Then I forget them. Since doing this, I've not had another work loose. I lost 2 before going through this routine. Gene Gruender Rainbow Chaser
Thanks for the response!
I know I was given the legal answer and I was doing the progressive checking thing stretching the time between checks. I appreciate the comment that boats are not cars but I also think that we should improve on existing setups where we can so future boat owners can benefit from the experience. In this case, I think Yanmar can fixed the problem for good if they make the shaft longer and use castle nuts that we can wire up. I appreciate the suggestion of the motorcycle washer that can be tapped up. Have not seen one of those. What do you call them and where can you get them? Thanks, Oliver.
I know I was given the legal answer and I was doing the progressive checking thing stretching the time between checks. I appreciate the comment that boats are not cars but I also think that we should improve on existing setups where we can so future boat owners can benefit from the experience. In this case, I think Yanmar can fixed the problem for good if they make the shaft longer and use castle nuts that we can wire up. I appreciate the suggestion of the motorcycle washer that can be tapped up. Have not seen one of those. What do you call them and where can you get them? Thanks, Oliver.
Tab lock washers
Tab Locks were used with great frequency on motorcycles. I sold parts way back when for Pretty much all the Japanese, English, German and a lot of others. It's long enough ago that I can't pull up a specific place where one would have been used. Best to start with a really good parts guy and explain the part to him. The tab lock is made of thin sheet steel. Think of an "O" with squares hanging off the sides. The washer goes over the stud or bolt. One tab is bent down around the part , the other is bent up over the flat of the nut, thus keeping the nut from turning. Ahah! Just thought of an example we'll all recognize! The washer used as a retainer on the nut that holds the propeller onto a Mercury outdrive is a form of tab washer. Check your local boat yard, then see a motorcycle shop. Don't bother with Harley, they prefer to see their parts vibrate off. If all else fails, thread locking compound is good too. (Locktite)
Tab Locks were used with great frequency on motorcycles. I sold parts way back when for Pretty much all the Japanese, English, German and a lot of others. It's long enough ago that I can't pull up a specific place where one would have been used. Best to start with a really good parts guy and explain the part to him. The tab lock is made of thin sheet steel. Think of an "O" with squares hanging off the sides. The washer goes over the stud or bolt. One tab is bent down around the part , the other is bent up over the flat of the nut, thus keeping the nut from turning. Ahah! Just thought of an example we'll all recognize! The washer used as a retainer on the nut that holds the propeller onto a Mercury outdrive is a form of tab washer. Check your local boat yard, then see a motorcycle shop. Don't bother with Harley, they prefer to see their parts vibrate off. If all else fails, thread locking compound is good too. (Locktite)
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