Previous Mast Step Repair; Opinions?

Thread starter #1
So i just determined that someone already attempted a mast step repair on the laser i just purchased.

Two things: water leaks out the bottom of the repair (i can see pooled water in the picture circled in red).
Also, there is a hold or two near the center. Top looks to be ok, but untouched.

What would the best route to repair this properly:

1. remove what has been done (have a feeling this will not be plausible)
a. I would like to do this, but I am guessing that removing any part of this repair will be an extreme hassle.
2. Re-cover/enforce what is there, injecting epoxy/hardener near the bottom where water is leaking until it oozes out
3. will covering the remaining portion of the mast from the inside with fiberglass and epoxy seal the holes in the center
4. reinforce the top with fiberglass/epoxy

anything else suggested here ? about a 1/4" of water does remain inside the mast hole at all times. I did pour a bunch of water down but it leaked into the hull

Mast Step (bottom)
IMG_20161001_114448694.jpg IMG_20161001_114510069.jpg

Top of mast tube
IMG_20161001_114339100.jpg IMG_20161001_114319404.jpg IMG_20161001_114314839.jpg



Active Member
My own sense- remove what you reasonably can - what is not structurally solid. Not worth getting really aggressive about it.

In my view, the critical function of that part of the boat is structural, load-bearing. With VERY rough calculations of moments on the boat (sailor hiking, etc), I've guesstimated that the joint between the mast tube and the bottom of the hull may carry shear loads in the order of magnitude of 1,000 pounds static or average, with peaks perhaps twice that as the boat pitches, heels, wind gusts, yada yada yada. So I'd be working first + foremost to assure that the structure is strong enuf to bear a load like that.

As to water leakage ... You'd "like" it to also be waterproof, cuz you don't want the hull filling with water and sinking. But, if it were to leak a quart of water in a hour, water is 2 lbs per quart; that'd add maybe 10 lbs to the boat in 5 hours - not a big deal. In my opinion, the big deal with water leaking there is that the older boats have a wooden donut around the foot of the mast tube. The leaked water infiltrates + soaks that wooden donut, which expands; then if the boat's stored in freezing conditions, it expands more. Then more water comes down the mast tube in the form of snow, rain, etc, and often goes thru multiple freeze-thaw-freeze cycles. So it ends up like water freezing + cracking a rock or cliff face, and the real bad result isn't the leak itself, it's that it cracks, compromises or destroys the fiberglass + the structural strength of that crucial joint. Then if or when it lets go, the mast falls over which tears the deck all to pieces, + now you have a major repair to keep the boat alive.

Just my 2 cents. Good luck with it.
For the reasons that cskudder mentioned I think you really want to seal the bottom of the mast tube. Others may have more and better suggestions as to how to do this, but it seems that after thoroughly cleaning and drying the relevant areas, you would want to pour some fairly low viscosity epoxy or polyester resin into the mast tube to seal it. After it's sealed be sure to install one of the metal disks made for this in the bottom of the mast tube. You should use some adhesive so that the disk stays in place. The metal disk prevents the mast from wearing through the bottom of the mast tube and it's my understanding that newer boats have this disk. And try to keep sand out of this area!

Then there is the structural integrity to address, which as stated above is the most important consideration. If you are not convinced the work by the previous owner is sufficient, it's not hard to add more glass cloth and resin. It looks like there is dried salt in that area, so I think you have some cleaning and thorough drying needed before adding material.

The tasks you are facing are not hard to do - and the inspection port is already there!
Thread starter #4
to be clear, are you suggesting to completely fill the mast tube with epoxy, and let it leak into the hull? I know in other posts this had been recommended by other members, but if i were to pour epoxy into the mast tube (assuming from outside the boat, or deck side), wouldn't it eventually dry at the bottom, and there would be less depth that the mast would slide down into (effectively raising the bottom of the mast tube)?

There is about a 1/4 " - 1/8" of water at the bottom of the mast tube that does not leak down into the hull. If i poured epoxy. this would all fill with epoxy and become solid.

And lastly, I've read there are different types of fiberglass and weights. Can some one explain or point me in the direction on choosing the right type of glass?

ty for replies!


Active Member
To your first question - you surely do NOT want to raise the bottom of the mast tube. I believe Rob's suggestion is probably to pour a little lo-viscosity epoxy into the mast tube, and let that drain out thru wherever the water leaks out, so that it will set in there where the leak is; or best left to him to come back on it. You might be able to minimize any accumulation in the bottom of the mast tube by trying to figure out which side of the mast tube the leak is on, and tilting the boat before you pour, so there's not a "puddle" at the bottom to solidify. Or maybe mop up the excess in the bottom of the tube after it "drains down", with paper towels or something. And I think Rob's suggestion of putting that metal plate down there is a real good one.

As to the type of epoxy- I used West System epoxy + glass + filler when repairing mine after it broke, cuz it's very high strength. I can't remember if they have a lo-viscosity product. If not, I'd think you can do the pour + leak seal with pretty much any kind of lo-viscosity epoxy you can find. Then roughen up the surfaces, and do the structural work on top of that with West System if you want, or something that's specifically high strength. Or maybe others can make more specific recommendations.
I would put just enough resin into the mast tube to seal the leak. Perhaps you can tip the hull as cskudder suggests. Even if your repair raised the mast 1/4" it doesn't seem to me that would cause a problem. Bear in mind also that since the mast tube was worn through, it's likely that the bottom was worn some. I have installed a metal disk and a plastic disk in my Lasers. The plastic disk is probably not really doing much. This raised the mast about 1/8" and I can't notice the difference. Perhaps someone has a better suggestion, but I think that's what I would do if I had such a leak.

Saeler79, I'm not sure I understand "completely fill the mast tube with epoxy". As above, I'd only pour in enough resin to achieve a seal. It seems in your case this would be at most 1/8" to 1/4" unless I'm completely misunderstanding.


Active Member
Yeah, just for the sake of clarity, want to make it clear I agree with Rob here- he said it better, can't imagine 1/4" will matter.
Thread starter #8
I mistyped when I said completely fill mast tube with epoxy. I was ultimately worried about causing the epoxy to puddle at the bottom (like mentioned) 1/4" or 1/8" inch and solidify, effectively shortening the depth of the mast tube. I think I understand where you both are going with this, I appreciate the help!
Pursuant to your last and Rob Hair's comments, you should be able to search this forum and there is information regarding the depth of the tube. I've seen a discussion before and think it is around 14+". I have seen in the boats I've worked on that there is a fairly large variation between each one. Therefore, you should be able to easily pour unthickened West System in the tube and build it up. The only potential problem is getting it clean for maximum strength, sealing and adhesion. Depending on how creative you are, you might be able to fabricate something to hold velcro or adhesive backed sandpaper on a log rod that could be attached to a drill. Then clean it up with acetone and you're good to go.

As for the outside of the tube, obviously, you've got an inspection port. When I do a mast tube, I use a Black & Decker Mouse electric sander with 80 grit paper which should fit through the hole. If it doesn't, it may be because the port is of the type that accommodates a fat bag. You can cut this out with a hacksaw blade. Hope this helps.