Re: Dripless shaft seal
Arlo,toggle quoted message Show quoted text
I have installed a few of the PSS dripless units made by PYI on customer boats. They are pretty well designed but I am going to stay with the original Amel installed Bronze packing gland which is a design that has served me well over 40 years of boating. True in theory the dripless glands can save you a little maintenance time as compared to the original packing gland but if you have the right wrenches, keep the gland clean and greased it isn’t much. The problem I see with the dripless designs that I am familiar with is that they are attached to the shaft log with a quite thin rubber bellows that does not seem to be reinforced with any fabric. The bellows shape provides a small amount of pressure to keep the bearing that seals out the water. Even something lightweight like the end of a mop handle can disturb the bellows and cause leakage. Also you can have salt deposits build up if the dripless unit sits for a long time that can prevent the unit from sealing after turning the shaft. I have had this happen on a customers boat, thankfully I always check the stuffing box or in this case the PSS gland which was dripping profusely after running the engine. Cleaning the sealing surfaces corrected the problem but this is not IMO a plug and play device that does not need to be watched carefully. The proper hose used to connect the bronze packing gland by comparison to the light bellows is perhaps 20X the thickness and well reinforced so much much stronger. A packing gland that has not been tightened often enough might drip a bit of water but if the bellows of a dripless fails completely there can be very significant ingress of water into the boat that is pretty much determined by the clearance between the shaft and the shaft log since there is nothing else keeping it out. A big upgrade to the old bronze packing gland is to use the really good white teflon packing which lasts much longer than the original flax material. With the Teflon packing you can almost end up with a dripless, especially with the addition of the grease injection. I am not familiar with the Las Drop that was suggested to you but it certainly sounds like an interesting design. Best of luck in making the best decision for your boat.