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Mast step issues


New Member
Hi first post here - have been lurking for quite a while!

New to me laser numbered 151xxx

When I first got it I flushed out the maststep and lots of black liquid came out - black enough to stain the deck and need scrubbing off

Have sailed it maybe 3 full days since and this last weekend as I stepped the mast more of this black gunk came out

I havent been cleaning or drying the masstep in between and its been holding water in the bottom

Mast step doesnt leak at all and the boat is totally watertight

There are some chips to the top where the maststep meets the deck but not very bad

My plan is to -

1. clean the mastsep with acetone
2. thoroughly dry it
3. clean the mast itself with acetone
4. use gelcoat filler to cover the chips
5. try to obtain some UHMW tape 1mm thick and wrap the mast upto the deck level
6. pop in a teflon disk into the mast step
7. after each sail dry and clean the maststep

I am assuming the black is from the aluminium mast itself

Have I missed something or am I on the right track?
Is the black gunk evidence of something more nefarious going on?

Can anyone recommend a supplier of the UHMW tape that will deliver to the UK?

Thanks in advance



5. try to obtain some UHMW tape 1mm thick and wrap the mast upto the deck level
Just an FYI: all you need is a single-layer wrap at the bottom and deck-level. Those are the only places that the mast (should) contact the mast-step tube.

I'm guessing the black gunk was probably ground up leaves and misc. crud that had accumulated in the bottom of the mast-step. Good to flush out. If it keeps coming back I would try to figure out what it is. I can't imagine you could generate much Aluminum oxide powder without grinding your mast away completely. Do you cover the boat between sails?

I would look for any wear on the gelcoat on the sides of the mast-step tube at the top and bottom. That's where all the side-load induced wear occurs.


Geoff S.


Upside down?
Staff member
Geoff's advice is sound. I wash out my step if I suspect that dirt (or salt) has gotten into it; a bit of overkill perhaps.

There is a potential problem with taping the mast at the bottom; discussed earlier on this forum. Some, including me, feel that it does more harm than good. If you decide to use tape, make sure that the area where one end of the tape touches the other end is 90 degrees away from where the mast touches the tube.


New Member
Thanks for the above - had not really appreciated the possibility of the tape causing more harm tbh

I do keep the boat covered but havent been emptying the maststep after each sail

Where I sail its usually windy and there are waves (even though inland!) and this, coupled with the fact that I do a fair bit of swimming (!) means the maststep usually has quite a bit of water in it when I have done

I do wonder if it just needs a really thorough clean and then a clean / dry after each sail?
After I have done that I will have a really good inspection and see what I can find wear wise

As regards the tape am really struggling to find some in the uk - its as rare as rocking horse sh@~!


New Member
Hi again

One other thing - if you do find wear inside the maststep is it a case of simply building up epoxy in there and sanding flat so as to thicken the wear surface?
Thanks in advance


If I remember right when I first got my used Laser I had the same issue with black stuff in the tube. I cleaned it out with an SOS pad and then cleaned the lower mast section with the same. After sailing it a few times there was nothing left. I would also suggest taking a garden hose and cleaning out the inside of the lower mast just in case there's any crud in there.

What I remember though is that once I cleaned it several times it then stayed clean. Can't recall why or what it was but it's no longer an issue. When I wash the boat I also clean the tube as a matter of course. Problem solved. :)

With respect to your mast step that's not leaking at all - if that's the case then, if it were my boat, I would measure the depth of the tube. It should be 14" exactly. If it's any deeper then that then it's worn. So, the real question is how deep is the tube?

My tube ground down to 14.25" and then started leaking and needed serious repair (see my sig file below). At first the leak would only show up under load when sailing in a strong wind. When I checked it at home it would hold water! This is because the crak would only open up under load. After 2 more sailing trips it cracked enough to finally show up at home by filling the tube with water.

So..... it's not always black and white!

However, if you're certain it's not leaking, and if it's not too deep, then I would consider buying some West and pouring it into the hole to get it back to 14". At that point I would install a stainless wear disk and also replace the plastic bottom piece on the lower mast. After that, I would call it done.

That's assuming your step isn't much deeper then 14" though. The problem with assumptions though is this - the depth of the tube is not the only issue. The tube also wears out at the lower front of the tube.

You have to picture the mast when loaded. When the mast is loaded it's pulled towards the rear of the boat. That means that the lower front of the tube will wear and the upper rear of the tube will wear. It's easy to see the upper rear but not the lower front.

So the depth of the tube doesn't tell the entire story. You might want to consider adding an inspection port at the front near the tube just so you can visually see what the actual step looks like and what the inside of the boat looks like. The one I installed cost $10 CDN and it's truly a 5 minute job that anyone can do. For years I was afraid of cutting a hole in my deck - that was stupid because when I finally got over my fear it was as easy as pie and I've been kicking myself for those wasted years! :D

I would kill two birds with one stone though and buy one of the $30 inspection ports, the ones that come with a bag. That way you have a waterproof bag to put your cell phone in, or car keys, or whatever other things you have that you don't want to get wet or lost in the event of a capsize.

At that point you can get a much better idea of what the mast step looks like as well as the interior of the boat. If the step looks good then you're hedging your bets that just pouring some West into the tube and installing a stainless steel wear disk is probably going to be all the preventative maintenance that you need.

On the other hand, if it later needs more serious attention you're still miles ahead because you've got the inspection port already installed. You can also keep a visually close eye on it as you sail it.

This is good preventative maintenance. You're not creating a big job unless it needs to be done. At the same time you're enhacing the boat by giving yourself a waterproof container and you're also giving yourself the ability to keep your eye on the step in the future.

Does that makes sense?


BTW, here's a picture that graphically shows the wearing area at the lower front of the tube :)
The reason why it's bright yellow is because the gelcoat has worn through. The orange area is unworn. That's how it wears when the mast is under load - at the lower front.



Former ISAF Laser Measurer
I always love it when people know exactly what size something is meant to be on a laser, when the information is not made public. ;)


I take it you're referring to the 14" mast tube depth I metioned above? :rolleyes:

Certainly I would understand that as an officiating body you might find that reference annoying given that you would be geared towards exact specs, however, the fact of the matter is that several people on the forum have measured many new boats and without exception, all of the mast tubes were 14" deep (or, so close that it doesn't matter).

If there's no published spec then there's no published spec, but we have to go by something to effect a repair so why not the depth of the tube on a large cross-section of new boats where the tubes aren't worn? :)

To me, that's just a common sense approach. ;) If there's no actual spec then it would seem to me to be the only approach. :D
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Former ISAF Laser Measurer
It just indicates that the boats that have been measured were that depth. It could be other boats from different molds and builders are different. I'm not disagreeing with the method used, just that it's meant to be "exactly 14 inches", as the builders manual will specify a measurement and a tolerance. We're just not privy to it, so we don't know what the exact measurement and tolerance should be.


Understood. So here's a question for you, what would be more advantageous from a performance perspective? Deeper or shallower or would it even make a difference?

If it's not a spec provided by the OEM then I would assume you can't rule on it? So if there was a performance improvement it would pass inspection provided it fit within the existing rules?


Former ISAF Laser Measurer
Actually I can rule on it, situations like this are covered in the rules, the rules give a procedure to follow.


I take it you're talking about this?


Repairs and preventative maintenance to the sail,
hull, deck, centreboard, rudder, mast, boom or
any fittings and fixings may be carried out without
violation of these Rules provided such repairs
are made in such a way that the essential shape,
characteristics or function of the original are not



I did ask here at TLF for the depth of the mast cavity, some weeks ago . Here is the link to the related thread:


Today, at our club, I did measure another 6 PSE-Laser of different age about the depth of the mast cavity. At the oldest Laser (1975) the depth is 36,7 cm and at the newest (2002) it is 36,2 cm. The meddle of the measurement of this depth at this 6 PSE Laser is 36,5 cm. BTW: I checked that the ruler that I used is okay, of course. It is curious, but it seems, at Lasers built in NA the depth is 1cm less than at PSE-hulls . I am absolutely sure, "49208" did measure correct and me, too.



I saw your post about mast tube depths and I added it to the collection I was gathering at the time - thanks for taking the time to measure them and report your findings :)

I tend to lend less weight to tube depths in used boats because, all things being equal, they will always be deeper then a new boat due to wear. I'm quite sure I ran across a post during my research where someone went and measured a series of new boats at a dealer and the depth was 14" across the board.

That's what I was getting at when I mentioned this above;

"If there's no published spec then there's no published spec, but we have to go by something to effect a repair so why not the depth of the tube on a large cross-section of new boats where the tubes aren't worn?"

I'm afaid the waters have been muddied a bit for the original poster - and the original answer. What I was trying to do was help him take a logical approach to his concerns so that he could avoid ripping his deck apart during a sailing excursion :cool:

The 1975 boat you measured had a tube depth of 14.4" - that's deep - really deep. The tube on my boat began leaking at 14.25" and I saw another user on the site mention leaking at the same depth.

I think we have to be careful about this. If future readers come in and read about boats with a 14.4" tube depth they might think that's OK. 14.4" ism in my opionion, way, way, out there and if it's not leaking now I would be really surprised. The real question is, do we know that that particular boat didn't leak water?

This comes back to the testing methodology and I think it would be way better to only report the tube depths of 100% new boats to avoid confusion and help narrow down what the spec actually appears to be.

For myself, I'm still curious as to how a ruling would work according to bylaw 3. I read it and can't seem to find anything other then what I quoted above. Perhaps some clarification other then just No would be of help :)

I'm also curious to know if my OEM spars would be still be legal if I changed the color of them.


Former ISAF Laser Measurer
Alan, I read By-law 3 (beginning on page 6 of 14 of the PDF), and I don't understand how you can rule on a mast step depth issue from it. What subtlety (or not so subtle) am I missing?
Ok, By-Law 3 in part states

2. (a) Hull The part of the hull of the yacht subject to protest shall be measured in accordance with the measurement directions attached as Schedule A and the same part of not less than five (5) other Lasers, chosen by the Race Committee as random samples, shall be measured in the same manner. The Race Committee shall select, if possible, Lasers which show no evidence of having been repaired or altered and which do not have inspection ports.

The arithmetic mean of the measurements of the boats chosen as the sample shall be calculated, and the protested yacht shall be disqualified if the difference between the mean value so determined and the measurement on the yacht subject to protest shall exceed the following values for the measurements indicated:

any point along the keel line (rocker): 2 mm
any other area of the hull: 3 mm
That give a measurer a method of measuring part of a hull which is under question / protest. For you guys, it gives you a method to determine the dimensions on a section of the hull, although personally I'd try to obtain a bigger sample size than just 5 boats, if I was doing a repair.

What you need to do is measurer probably 10, but a minimum of 5 newish boats, with the above restrictions and determine the average mast step depth. For the boat which is then being repaired, the depth must end up within +/- 3mm of that average depth you measured. I'd suggest only one person does the measuring, so the same equipment and method is used each time, thus elimination a whole heap of measurement error sources. This method isn't exact and may not give the same value as indicated in the builders manual, but it accurate enough for it not to raise attention.


Wierd. You must be quoting an entirely different rulebook then then one in your sig file. That's probably why neither myself nor Merrily can seem to follow along...

Either way, it sounds like the rules basically parrot my earlier posts, measure a bunch of new boats and use that figure :)


Former ISAF Laser Measurer
Well, I did say earlier that I disagreed with your wording and not the method. My posts contain a link through to the Laser Class Measurement Rules and not through to the Class Constitution which include the by-laws, measurement rules etc. Members of the Laser Class Association receive (or should) a copy of the Laser Class Handbook, where they are included every time they are published, which these days is annually.


New Member
thanks for the detailed replies

since my original post I have now had a looky and found wear through the gelcoat at the top of the maststep where it loads up against the spar

i intend to layer / sand / layer /sand etc etc with gelcoat - maybe a few coats to build up a decent layer

havent yet measured the step but will do so and (warily!) report back

becasuse its 151xxx as I understand it it should have the metal disc when built?

thanks - great forum and I think it is great that people are passionate about lasers!

my club in the North of the UK has an active and growing laser fleet which is brilliant



Hi Nick;

I don't know when Laser started adding the stainless disks to boats - maybe someone else in this thread knows? Hopefully it does have one. I would think you'd be able to see it unless the hole is like totally filled with black gunk.

Even if it has a disk I'd still be interested to know the depth. Does anyone know when Laser started adding disks? AlanD maybe?