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Mast Step Dimensions and repair

laser8017

New Member
The mast tube on my laser new $250 laser has been damaged and poorly repaired. I am looking to replace the mast step tube but the repair kits available seem to replace a huge section of deck and make your boat look as though it had massive damage and was repaired. Are there any places that just sell the mast tube. I though about making a plug and creating my own part but I read that the mast step transitions from oval to round and since my boat is damaged I can't take a plug off of my boat. I work in a composites research lab so I think could make the part if someone knows the exact shape of the tube. An alternative way for me to find out the shape would be to have someone measure the width mast tube and then tell me the mast rake with the mast pulled forward and backward to determine how much play is in the mast from the oval section. With this information I can draw the oval that makes the mast rake correct.


Questions:

Is there a smaller mast step repair kit that doesn't cut out a huge section of deck?

Does anyone have a plug of a mast step or know the dimensions of the part?

What is the ideal mast rake on a new/newer boat with the mast pushed forward and back?

Thanks for any info
Paul
 

Wavedancer

Upside down?
Staff member
Did you see and study this recent thread:
http://www.laserforum.org/showthread.php?t=29277

Corolla tackled, what seemed to me, a very difficult job.

I honestly believe that trying to get the rake etc. perfect is going to be difficult. And substituting a round, rather than an oval, tube makes sense to me. Of course, corolla ended up with a non class-legal boat. Not sure what your plans are. Perhaps it is possible to manufacture an oval tube?
Or salvage a tube from a boat about to be junked...

PS: The corolla thread has the info on the mast rake (in a pdf).
 

Wavedancer

Upside down?
Staff member
Sorry; that link goes way back; more than ten years ago.

Please specify what you need to know; there are many threads related to mast tube and step repairs. Did you try the SEARCH function?
 

b12

New Member
I did - yes, I know it goes back a little (and so does this one) but the mast tubes are still wearing out, even after all this time...
See pic for what mine looks like, mostly worn gelcoat on the inside and some surface chips/cracking but all still sound:
For the tube I'm thinking to lay up a couple of layers of CSM on the areas worn completely through and then a few coats of gelcoat on the whole tube as the new wear layer.
What are your thoughts if you don't mind Wavedancer?
Also is there anywhere that gives the tube dimensions that you or anyone there is aware of please?
Worn tube.jpg
 

b12

New Member
This thread What Is The Diameter Of The Mast Pocket On The Laser? and LooserLu discuss the diameter of the mast:
Definitely diameter 64 millimeter (about 2.5 US") will work.
Just to mention: At the Laser, the mast-tube is an oval hole -> means: the smaller diameter (thats to the sides, aka starboard/portside) is as said before: ~64 mm (+/- 1 mm tolerance).


But still the question remained unanswered... If the mast is standard 2.5inches/63.5mm diameter, the top of the tube at the minor axis will be something like 65mm and the major axis will be something like 75mm. Furthermore it looks to me like the tube then tapers to a circle. Ie the mast sits quite snugly at the base of the tube with almost no play. Can anyone give a categorical please??
 

b12

New Member
Wavedancer, forgot to mention my hull is a 2004 build (179555 – 182213) and was raced in state and national events in it's early years, pretty hard I expect. The rest of the boat is still in first class condition so for me it's worth getting it as right as I can.

Also mast rake (eg see Top Reads 2016 #1stplace - My Laser Mast Rake. - Rooster blog) is a consideration. UK boats mast rake of 3820mm and Aus mast rake of 3830mm seem to be the target for building the layers back up, thoughts?
 

LaLi

Well-Known Member
At the club right now, and measured on my own (PSE 1990) boat the top end of the mast step is 74.7 mm long and 66.0 mm wide. The radius that the opening is rounded to is about 3 mm. The original lower (Standard/ILCA 7) mast is 63.5 thick, and there’s maybe two mm of play at the bottom.

If your numbers don’t differ much from those and the step doesn’t leak, I wouldn’t do anything to it. It may look bad with so much of the gelcoat gone, but I don’t think it’s going to break down anytime soon. Even if it were to, I’d rather fix it from the inside.

But how did it get that way? This is the same view of my boat that is 14 years older (and sailed in nine Masters Nationals among countless other regattas):

0E5FFDCB-32B5-4FD1-91A0-9D68AFF0C7CB.jpeg
_
 

Wavedancer

Upside down?
Staff member
I did - yes, I know it goes back a little (and so does this one) but the mast tubes are still wearing out, even after all this time...
See pic for what mine looks like, mostly worn gelcoat on the inside and some surface chips/cracking but all still sound:
For the tube I'm thinking to lay up a couple of layers of CSM on the areas worn completely through and then a few coats of gelcoat on the whole tube as the new wear layer.
What are your thoughts if you don't mind Wavedancer?
Also is there anywhere that gives the tube dimensions that you or anyone there is aware of please?
View attachment 45586
That's not a bad plan, but I would do something simpler by just covering the exposed fiberglass. I am assuming the tube does not leak.
Here is some recent advice from the Sunfish forum:
(1) Mast cup issue | SailingForums.com

Please note that Signal Charlie has a LOT of experience; I don't!
 

b12

New Member
This thread What Is The Diameter Of The Mast Pocket On The Laser? and LooserLu discuss the diameter of the mast:
Definitely diameter 64 millimeter (about 2.5 US") will work.
Just to mention: At the Laser, the mast-tube is an oval hole -> means: the smaller diameter (thats to the sides, aka starboard/portside) is as said before: ~64 mm (+/- 1 mm tolerance).


But still the question remained unanswered... If the mast is standard 2.5inches/63.5mm diameter, the top of the tube at the minor axis will be something like 65mm and the major axis will be something like 75mm. Furthermore it looks to me like the tube then tapers to a circle. Ie the mast sits quite snugly at the base of the tube with almost no play. Can anyone give a categorical please??
Update: I was assuming "Definitely diameter 64 millimeter
At the club right now, and measured on my own (PSE 1990) boat the top end of the mast step is 74.7 mm long and 66.0 mm wide. The radius that the opening is rounded to is about 3 mm. The original lower (Standard/ILCA 7) mast is 63.5 thick, and there’s maybe two mm of play at the bottom.

If your numbers don’t differ much from those and the step doesn’t leak, I wouldn’t do anything to it. It may look bad with so much of the gelcoat gone, but I don’t think it’s going to break down anytime soon. Even if it were to, I’d rather fix it from the inside.

But how did it get that way? This is the same view of my boat that is 14 years older (and sailed in nine Masters Nationals among countless other regattas):

View attachment 45597

Thanks LaLi for the hard data and advice, much appreciated.
You pose a good question "But how did it get that way?"... Got me thinking and got out the digital caliper and it seems that the radial mast diameter is 61.2mm diameter vs the standard mast diameter 63.7mm. Given that the boat has probably done 90% of it's work as a radial, I'm thinking the extreme wear maybe due to the additional ~2.5mm of "room" that the mast can slosh around in the tube. What % did you sail as standard vs radial please?
 

LaLi

Well-Known Member
Given that the boat has probably done 90% of it's work as a radial, I'm thinking the extreme wear maybe due to the additional ~2.5mm of "room" that the mast can slosh around in the tube. What % did you sail as standard vs radial please?
I have both rigs but have never raced with the Radial. Way more than 90 % of the sailing time has been with the Standard.

I don't think it matters which section one uses, though. In fact, I'm not sure that either should even touch most of the area where your gelcoat has worn off. The wear on my (and many other) masts indicate that there's significant abrasive contact only at the aft edge at deck level and at the forward edge at the bottom. Neither area extends much more than about 5 cm vertically. What do your masts look like?

_
 

b12

New Member
That's not a bad plan, but I would do something simpler by just covering the exposed fiberglass. I am assuming the tube does not leak.
Here is some recent advice from the Sunfish forum:
(1) Mast cup issue | SailingForums.com

Please note that Signal Charlie has a LOT of experience; I don't!
Thanks again Wavedancer,
The tube does not leak
At the club right now, and measured on my own (PSE 1990) boat the top end of the mast step is 74.7 mm long and 66.0 mm wide. The radius that the opening is rounded to is about 3 mm. The original lower (Standard/ILCA 7) mast is 63.5 thick, and there’s maybe two mm of play at the bottom.

If your numbers don’t differ much from those and the step doesn’t leak, I wouldn’t do anything to it. It may look bad with so much of the gelcoat gone, but I don’t think it’s going to break down anytime soon. Even if it were to, I’d rather fix it from the inside.

But how did it get that way? This is the same view of my boat that is 14 years older (and sailed in nine Masters Nationals among countless other regattas):

View attachment 45597
_
Just got some great info back from Performance Sailcraft Pty Ltd (Australia). Home of the ILCA / Laser dinghy since 1964. www.psasailing.com.au... categorically.
Lower section diameter is dependent upon the rig as follows:
  • Lower section 7 (Std) & 4 (4.7) diameter:
    • Min OD – 62.9 mm
    • Max OD – 64.5 mm
  • Lower section 6 (Radial) diameter:
    • Min OD 60.26mm
    • Mx OD 61.46 mm
The upper mast step measurements are / should be as follows:
  • Length – 74.5 mm (acceptable range 72.8mm to 75.5mm)
  • Width – 65.5 mm (acceptable range 64.3 mm to 67 mm)
The lower/step end mast post diameter is 65.5mm (with a range 63.5 mm to 66 mm).

The good news is that my lower mast sections are within spec, albeit with about 0.5mm wear on the 2 rub points on the radial must section.
On the other hand the top of my mast step is 76.0mm long x 68.3mm wide, both exceeding the upper range, also the bottom of the mast step is 67/69mm diameter again exceeding the upper range (it is supposed to be round but unevenly worn), so I will have to do something as previously thought.

Will have to make up 1.5 - 4mm at various points in the tube. How to do that?
 

b12

New Member
That's not a bad plan, but I would do something simpler by just covering the exposed fiberglass. I am assuming the tube does not leak.
Here is some recent advice from the Sunfish forum:
(1) Mast cup issue | SailingForums.com

Please note that Signal Charlie has a LOT of experience; I don't!
I have both rigs but have never raced with the Radial. Way more than 90 % of the sailing time has been with the Standard.

I don't think it matters which section one uses, though. In fact, I'm not sure that either should even touch most of the area where your gelcoat has worn off. The wear on my (and many other) masts indicate that there's significant abrasive contact only at the aft edge at deck level and at the forward edge at the bottom. Neither area extends much more than about 5 cm vertically. What do your masts look like?

_
Hi LaLi - the radial mast section is perhaps 0.5mm worn as per pics. The standard section hardly has a mark, confirming the % use as earlier. What do you think of the ware in the radial section?

Until something more plausible comes along I think I'll stick by the cause being that the radial is 2.5mm diameter less than the standard section so there is A LOT more movement of the mast in the tube - a bit of a design flaw if you ask me - maybe the radial should have had a sleeve/wrap on the bottom 360mm to at least bring it out to a similar diameter as the standard section.
 

Attachments

LaLi

Well-Known Member
I don't find the extra "sloshing" of the Radial section a plausible explanation for the extra wear (which, in light of the numbers, has been considerable). That is, I don't see how the friction would increase by having slightly more space on the opposite side. Also it looks like the mast is worn at the "normal" places, which doesn't match the pattern in the mast step. Still a bit of a mystery.

But if you're really outside the production tolerances, you do need to restore the step somehow. If PSA didn't already give tips on how to do it, you might want to ask them. They might even do it themselves... at a price of course.

As I said before, the step probably won't self-destruct anytime soon, despite the damage. The wear at the deck level on the mast is more worrying; the Radial section wall isn't very thick, and they're known to break right there. I'd apply some protection right away to stop the deterioration, but eventually you may have to get a new lower mast.

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