Mast Boot and Chain Plate Deck Penetrations

I think that all of us who live aboard and cruise strive to keep our living quarters and belongings dry. But no matter how hard we endeavour to seal out the elements, the odd drop or two seems to make its way inside every now and then.

While mast boots and chain plate deck penetrations can be a couple of the worst culprits, I am pleased to report that, so far, they haven’t been much of a problem on Moonshadow.

I can’t take any credit for my chain plate’s water tightness. They were sealed well at the factory with Sikkaflex or a similar product which, after 16 years is still performing well. It this case, my thinking is “if it ain’t leaking, don’t fix it.”

ChainPlateChainplates and deck plates sealed with Sikka

That said, when we repainted Moonshadow in ’99, we resealed the surrounding deck plates with Sikka. These keep the bulk of the deck wash and UV rays away from the seal system underneath that is doing most of the work.

For the mast boot, we have a three-part system.

First, supporting the mast inside the collar is a product called “Spartite.” After the new mast (1999) was stepped and the rig adjusted, the riggers set the precise fore & aft and athwartships positions of the mast at deck level with some additional lines. A putty “dam” was formed around the mast in the bottom of the mast collar and the two-part Spartite mixture was poured into the top of the mast collar around the mast.Spartight

Spartite between the mast and the collar

When the Spartite sets, in about 24 hours, it provides a permanent support for the rig at the mast collar, as well as providing a more or less watertight seal around the mast.

In addition, we also have the typical rubber boot fastened around the base of the mast and over the top of the collar with large diameter hose clamps. In our case, have used a purpose built boot that is fitted to the mast and the collar. Note that the top of the boot is turned inside out to cover the hose clamp. The only snafu about this type of boot is that it must be slipped over the bottom of the mast before it is stepped in the yacht.

MastBootMast boot

Lastly, to protect the mast boot from the pressure of deck wash and UV rays, I have also installed an acrylic canvas boot, which also serves to make the whole system look tidy.

BootCoverAn acrylic canvas cover to protect the mast boot from spray and UV

While I have had no evidence of leaking at the mast collar, sometimes when we are power reaching, we get a bit of a creaking noise at the mast collar as the boat flexes in a seaway. All in all, I would trade this for leaking any day.


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