Saildrives?

[Savanna]

Hi Sailorman Ed,
Sounds like the same issue as I had with a newly purchased catamaran about a year ago. The boat (a 38ft Maxim) came equipped with a couple of Yanmar SD20 saildrives, and the boots were coming off. I daresay that different makes of catamaran may have different arrangements for seating the saildrives, but mine are mounted on the top edge of a fiberglass tube (about 10 inches in diameter) which is an integral part of the hull, and which flares out to about 12 inches wide where the shaft of the saildrive exits below the bottom of the boat.

In my case I felt that one of the reasons that the boots were coming off was that the area of the boot actually glued to the bottom of the boat was minimal, and hence I had 2 wooden inserts made up (from 2 inch thick wood) for each saildrive which were glued into the shaft either side of the saildrive, and flush with the bottom of the hull. If you do this, take care that sufficient space is left to extract the saildrive upwards if you ever need to do this. The wooden inserts, once faired with the bottom of the hull, then provided a significantly increased surface area to which the new boots could be glued.

I would recommend new boots, and gluing these down after the surface to be glued has been thoroughly cleaned, and if necessary filled and faired to make it even.

The other maintenance things I did at the same time were to clean the saildrive up inside the tube as far as I could, and have it painted with a suitable anti corrosion paint (the sail drives are alloy so a special paint is required), and (if you raw water cooling system draws in sea water through the saildrive) to thoroughly clean out the water intake to ensure that there is plenty of cooling water being drawn up into the cooling system.

Best of luck with your repairs.

[DotDun]

We fabricated sheet plastic (~1/8") the same size as the boot and screwed it into the hull over the boot to make sure it won't come off.

[Sailorman Ed]

Thanks but I really should have said "gaskets" or whatever the term to seal water out of the hull. The Po had significant water leaking into the hull just prior to being hauled. I know there are 2 of them and I also know there should be a sensor. Will also replace the "boot" while I am in there. So what is the procedure to replace both "gaskets"?
Ed

[DotDun]

Originally Posted by Sailorman Ed

Thanks but I really should have said "gaskets" or whatever the term to seal water out of the hull. The Po had significant water leaking into the hull just prior to being hauled. I know there are 2 of them and I also know there should be a sensor. Will also replace the "boot" while I am in there. So what is the procedure to replace both "gaskets"?
Ed

I've never done it (yet), but looking at the service manual, it appears the saildrive has to be removed from the boat as the upper and lower gear housings need to be separated.

[dennisail]

Me new boat has SD20s. I have never had anything to do with sail drives, but I figured out how to pull the bottom sections apart with ease. Takes about 15 min. The seals look like regular bearing seals which will cost about $10 from any bearing shop and the oil is about $35 for both sail drives. They look very simple in operation to me and with regular oil checks it will be easy to see if the oil is getting milky from sea water.

The oil did look a bit milky, but not too bad. I didn't see any actual water. However an odd thing was when we took the dipstick out oil actually bubbled out over the opening. Possibly a lot of water mixed with the oil. Who knows. But the drain plug on that saildrive was missing its rubber O ring.

Here is a vid of someone doing their seals. Fast forward to 1:40 and see what comes out of there! Looks like about 2L of water followed buy milky oil. But the boat looks fairly new?

Yanmar SD20 Saildrive - YouTube

[thomm225]

I have been looking at a lot of boats but really like this Wauquiez Gladiateur. It has a saildrive.

According to the prior posts, I should at least have the seals changed or checked and the lower unit oil replaced if needed. I plan on paying a mechanic the first time then doing it myself after the purchase. The engine and saildrive were installed in 2008. The boat has been in storage the last 2 years.

1983 Wauquiez Gladiateur 33 Sail Boat For Sale - www.yachtworld.com

[Sailorman Ed]

Dennisale - thanks for the Youtube link. I am amazed what you can find there. Looks pretty straightforward. I will pull that section and source the seals and keep a spare set with me. Industrial supply would have all these and be much cheaper than yanmar. I guess all that water for for the "water cooled" bearings.
Ed

[DotDun]

Originally Posted by Sailorman Ed

Dennisale - thanks for the Youtube link. I am amazed what you can find there. Looks pretty straightforward. I will pull that section and source the seals and keep a spare set with me. Industrial supply would have all these and be much cheaper than yanmar. I guess all that water for for the "water cooled" bearings.
Ed

When you figure out the size for the lip seals, please share.

BTW, (2) lip seals, (2) o-rings, (1) o-ring for the plug, (1) spacer between the lip seals is ~$24 from Yanmar include shipping/tax in the US.

[dennisail]

That is cheap enough to not even bother going to the bearing shop. But since the bearing shop is closer I will go there anyway. You dont need to figure anything out. At least not at mt bearing shop. They guys there know what they are talking about and if you bring the old parts and gear set in they will find the right parts for you.

[Cheechako]

Originally Posted by tamicatana

Thanks Cotemar, I knew about LanoCote. That's fairly expensive, esp. since it'll be gone as soon as you crank the boat.

Here's the discussion I'd found. Fella in Daytona Beach using surfboard wax:
http://www.cruisersforum.com/forums/...tml#post967870

OK, I tried Lanocote and Spray silicone on the two props on my 42 catamaran. I applied them on bare bronze Max Props. One side got the Lanolin, the other a full can, in layers, of silicone spray. We had been having growth problems all the way down the Caribe to Trini so I though what the heck I'll experiment.

I didnt find much diference in either side and didnt find a big advantage over bare bronze either. I love lanolin and use it lots of places but cant vouch for it too much here.

[thomm225]

Good article on saildrive vs conventional.

It answered all my questions most of which were covered above, but this guy does it without getting into a urinating contest.

All About Saildrives - Articles - boats.com

[robert sailor]

Good write up

[colemj]

The article is decently balanced, but contains errors.

1. The raw water system is not like an outboard's. On a saildrive, there is simply a thru-hull added to the mounting casting. This is really no different than putting a thruhull in the hull itself. The saildrive contains no waterpump or other cooling water system components - it simply contains a hole.

2. That picture of the corroded ring zincs on the propeller, and the warning about it, is very misleading. Those only exist on certain versions of Volvo folding props and are not very important at all. They are small and thin, and go quickly because there is hardly any zinc there. Other Volvo and non-Volvo props do not have them at all and do not suffer any problems. The main zinc is really the only one of importance.

3. The picture of the single-piece main zinc is from an older drive. Both Yanmar and Volvo's current drives have split zincs that allow easy changing under water. The advice that you can get split zincs from boatzincs.com and use them in place of the single zinc is wrong. There is/was a company that made a converter kit for this, but it is/was very expensive.

4. Volvo does not use a dual-boot or provide a water sensor. Yanmar does, but the articles mentions Volvo having this several times.

5. The warning and concern about the main rubber boot seal is overblown. I have yet to find a single incident where this seal has breached - other than a couple of cases of boats going up onto rocks and punching the drives out of the boat. In non-catastrophic usage, these seals are robust and last a long time.

6. The warning about bronze folding propellers is also misleading. The most common folders sold with Volvo and Yanmar saildrives are the Volvo props. These are electrically isolated from the rest of the system by a rubber hub bushing - similar to outboard props. I do not know about other brands of folding props.

Mark

[SeaKing]

I have an older sd31 yanmar, no cone clutches. At the suggestion of another poster here I have created a header tank for the oil in the sail drive . I has to drill a hole in the cap to install a tube for the oil to go into the drive. This tank is above the water line creating a positive pressure in the drive . If the seals fail only drops of oil escape into the water , I have had the system for over five years and non problems

My understanding the newer large drive you can at least change the oil from above , my old one cannot. On the cones they can be resurfaced without pulling the boat . The engine can be loosened and moved away from the drive enough to access the cones to relap them with valve grinding paste . I think the problem comes from improper shifting practices by the operators.

[DotDun]

Originally Posted by SeaKing

I have an older sd31 yanmar, no cone clutches. At the suggestion of another poster here I have created a header tank for the oil in the sail drive . I has to drill a hole in the cap to install a tube for the oil to go into the drive. This tank is above the water line creating a positive pressure in the drive . If the seals fail only drops of oil escape into the water , I have had the system for over five years and non problems

My understanding the newer large drive you can at least change the oil from above , my old one cannot. On the cones they can be resurfaced without pulling the boat . The engine can be loosened and moved away from the drive enough to access the cones to relap them with valve grinding paste . I think the problem comes from improper shifting practices by the operators.

I'm not convinced the 'header tank' is a solution to the issue. As the lip seal wears the prop shaft it can't seal as well as when the shaft is new, hence water intrusion. IMO, the intrusion happens due to the drive case being sealed, it heats up during use creating a positive pressure, then when it cools down it creates a vacuum, and that is when it sucks water past the seal/worn shaft. This makes me think simply venting the drive would stop the pressure/vacuum situation. Drill a small hole (1/8"?) in the plastic cap and keep the oil level within range on the dipstick. This would allow for air movement, but oil shouldn't get high enough to leak. If in fact the shaft is worn such that water can get past the seal while in storage (no temperature swings), then it's time to address the worn shaft (replace or speed-sleeve).

Just my opinion!