The Offshore Voyaging Reference Site

Waterboot Mast/Deck Seal

No leaks down the exterior of the mast below the partners. Period. That’s what Waterboot promises and what it delivers.

The Waterboot is computer cut to your measurements (based on their instructions) from a durable, lightweight, 100% UV resistant, rubbery material with a Velcro closure. You fit the boot around the mast, close the Velcro, and then run a bead of silicone around the top and along the Velcro closure, filling any voids. Waterboot suggests that you might also wish to use self-amalgamating tape or a stainless steel hose clamp around the top of the boot. We use a hose clamp and with this setup we have absolutely no leaking down the mast into the boat.

We purchased our last Waterboot when we installed the new Hall Spars mast in 2006, not because the old boot had failed but because the mast shape was different and the Waterboot needs to fit snugly to work. After six years the Waterboot is still in great condition. Do note, however, that, being of the belt and suspenders persuasion, we cover the Waterboot with a custom-made (by yours truly) Sunbrella cover to further protect it from UV damage and nicks or cuts.

Does anyone else have experience with the Waterboot or any other type of mast boot? Please leave a comment.

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Jerry Levy

Being of the belt and suspenders persuasion, do you keep a spare aboard the boat?

John Harries

Hi Jerry,

No, although we carry spares for a lot of stuff, not that.


Hi, our keel stepped mast leaks, but it mostly seems to come down the inside of the mast. Do you have any sort of internal system (mast dam?).

By its nature, inside the mast leaks get channelled down into the mast step in the bilge so are less important but it would be nice to keep the bilges dry if possible.


John Harries

Hi Dave,

Yes, that’s always a problem. Some masts have a dam inside the mast above the deck with small drain holes. However, with keel stepped masts, its very difficult to get the dam watertight.

So we have a dam about 12-inches up from the mast step that has a drain hose that is then plumbed into the same sump as our anchor locker. At Hall Spars, they call it the “Brady Stop” after the technician who invented it. Works great and would be easy to retrofit to an existing mast.

David Nutt

When refitting Danza’s mast I made a dam about 18″ from the bottom of the mast similar to what John calls the ‘Brady Stop’. The drain drops down into the bilge sump eliminating water accumulation at the base of the mast.

Gary Schwarzman

We’ve always used a sheet of rubber (neoprene, although I’ve heard of folks using truck inner tubes) seized in place with seine twine. Seems like it would work just as well as the manufactured product, and the price is right. But as you do, we cover it with a sunbrella boot for backup, UV protection, and appearance.

John Harries

Hi Garry, welcome back.

Yes, I think that works great when the mast and deck flange are not to different in shape or size. However, the clever part of the Waterboot is that the inventor has come up with a computer program that allows him to cut the material to a complex curve that fits the mast and deck flange well when wrapped without stretching the material too much. Sounds like a solution looking for a problem, I know. But it really does work great.

Gary Schwarzman

Hi John,

I wouldn’t belabor the point, but I must leap to support Phyllis: she seems to have made a very nice job of the Sunbrella cover, presumably without the aid of a computer.


The leaky mast issue plagued us for the first few years of cruising. One day we were sitting on the deck trying yet another “solution” when another cruiser dinghied by and said – “I know a solution that will fix that”. We’re all ears. His recommendation was to use a common household toilet wax ring. For more on the fix, here’s a post I did on the subject:



Once we used a liquid soft setting compound (name forgotten) that forms a completely watertight seal at the deck/cabin roof mast entry. It is supposed to be easy release for removing the mast. Well the problem was, the mast had a taper and therefore so did the seal and pulling it made it tighter! apparently it was lots of work to free the mast! So I think John’s system that lasted six years is the way to go.

John Harries

Hi Viv,

I think we use the same system you are referring to. It is called Spartite and it replaces the wooden chocks we all used to use at the partners (hole through the deck).

While we love Spartite for the nice even support it gives the mast and the lack of squeaking that we used to get with wood chocks, we have found that water will still seep down between the Spartite and the mast and partners. Perhaps that is because we liberally smeared both with petroleum jelly before pouring the Spartite, so that we can get it out. We also used two plastic strips to act as separators when pouring, one either side, so that the collar can be removed in two halves.

In short, while Spartite claim to solve the leaking problems as well as chocking, we have found, after 10 years of use, that that’s not really true in the real world.

Also, as you say, if the partners or mast are tapered the wrong way, you are in a world of hurt when you have to remove the mast.


I used neoprene (wet suit material) with a hose clamp at the top. Because the mast and deck collar are very different sizes and shapes (oval and rectangular, respectively), I had to cut darts in the material at each corner of the deck collar and taper the neoprene to fit the mast. I glued the seams with wet suit adhesive, which makes a strong and watertight seam. To fix the boot to the rectangular collar, I used strips of aluminum stock screwed to the collar with machine screws. Because neoprene is subject to UV degradation I covered the boot with a sunbrella cover.

David Nutt

I wrap the mast with shrink wrap material and then shrink it down with a heat gun, cover it with a sunbrella boot and have no leaks. OK, I do run several layers of white shrink wrap tape on the mast and at the collar. Cheap and successful…

Steve James

The late Linda Lucas, s/v Covenant, taught me this and it has worked perfectly for twelve years. Take a standard ace bandage from the pharmacy and wrap it multiple times around the mast collar up onto the mast. Then paint multiple coats of liquid rubber onto the ace bandage. The liquid rubber product is the stuff youbuy in a small can at the hardware store that is more commonly used to coat the handles of small tools. A small glob of silicon in the mast track slot makes it water tight until the next time we pull the rig. Total cost is about $5. We also protect this from the UV with a Sunbrella cover.