400: SD 50 rubber gasket

[feebs]

Hi,

My L400 doesn't have a rubber gasket fitted to either SD, as shown in attached photos. I get a fair amount on oyster growth in space between SD covering plate & hull. Last haul out my shipwrights said that it was unusual not to have a rubber gasket installed & that if it was, growth would be a lot less.

My questions are:

Do other Lagoons with SD50's have these fitted as standard ie did Lagoon just forget to install on my L400?

Are these rubber gaskets effect in reducing/eliminating growth above covering plate?

How are covering plates attached to hull & how easy will they be to remove, with breaking them?

Thanks in advance

[tuskie]

Hi Feebs,
If they forgot that lower rubber gasket on your's, then they made the same mistake on mine. Perhaps there is a reason that these are not fitted?

The plate that you have shown in your photo, IIRC is called a "fairing plate" and just assists water flow around the legs from becoming turbulent. I haven't removed mine, but am told that it is only Sikaflexed on. A sharp flexible blade should remove.

Marine growth on saildrive ĺegs concerns me more on the internal passages than externally.

Cheers

[feebs]

Bonsoir Tuskie,

My main concern is that with Sydney harbour being so productive these days, oysters are growing above fairing plate - these are of good eating size, but too large to drag out between fairing plate & SD leg. Now will these oysters rub on SD diaphragm leading to early failure of diaphragm? Trying to put antifouling in this area is near impossible.

Any thoughts, apart from sailing over to join you in better waters⛵️

Yes concur with growth in internal passages of SD.

[mfotis]

For what its worth, I have a 2004 410 and mine was "missing" these as well and the surveyor said I should get them replaced when possible. Both for the reasons you have stated and because not having them supposedly increases drag. The factory ones are reportedly pretty pricey and I've had someone recommend to me that one could accomplish the same thing by cutting and affixing a sturdy mud flap (like found on tractor trailers). I have not attempted this yet but will take a look at it here within the next week or so when I haul out the boat.

[DotDun]

Most likely installed but fell off. The standard Yanmar piece is glued to the hull. IMO, most installers either don't use the right glue or follow the correct procedure. Fabricating thin plastic covers screwed into the hull keeps them in place.

[tuskie]

Originally Posted by DotDun

Most likely installed but fell off. The standard Yanmar piece is glued to the hull. IMO, most installers either don't use the right glue or follow the correct procedure. Fabricating thin plastic covers screwed into the hull keeps them in place.

That may well be corect, DD but if so the original rubber boots should be sloshing about above the Lagoon fibreglass faiŕing plates?

Do you think oysters and other marine growth in this area could damage the main hull to saildrive seal?

[tuskie]

Originally Posted by feebs

Bonsoir Tuskie,

My main concern is that with Sydney harbour being so productive these days, oysters are growing above fairing plate - these are of good eating size, but too large to drag out between fairing plate & SD leg.

If you could remove the fairing plate, you could eat those delicious Sydney Rock Oysters?

Bon appatite!

[DotDun]

Originally Posted by tuskie

That may well be corect, DD but if so the original rubber boots should be sloshing about above the Lagoon fibreglass faiŕing plates?

Do you think oysters and other marine growth in this area could damage the main hull to saildrive seal?

The original lower rubber seals is quite thin, maybe 1/8-3/16". Once the glue lets loose, it'll tear off pretty quick.

Large growth above the outer hull would bother me. The main seal is at least 1/2" thick, but I wouldn't want sharp objects beating it up.

[Privilege]

Me and other SD owners have resorted to fabricating our own gaskets. I used the rubber from a trucks mud-flaps and glued them in place using 5200. They have lasted a couple of seasons so far.

[mfotis]

Did you use one per side or did you sandwich two together per side?

[Privilege]

I'm not sure why you would sandwich two. I used one per side. They are just thin rubber mats designed to stop critters from getting up into the drive-well. You cut out the shape of the leg of the drive and with the propeller removed, force them up over the lower drive. I glued them in place and just used the extra 4200 to fair the edges so that water is less likely to peel them back. You can buy the Yanmar ones, they are very thin and easy to use but why pay the extra?

[hmeilman]

Lagoon probably omits the gaskets to save money. Putting them on keeps growth out of the upper chamber. Cleaning the intakes of the sail drives should be a regular and frequent maintenance item. Overheating is the first sign that they are clogged.