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Old 26-11-2015, 20:51   #1
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Deck under mast cracks.

Under the mast in the cabin of my 1976 28' Sovereign CC, the fiberglass looks to have some type of white compound that was used at some point (not sure if it is original or not since it can be found in a lot of places mid cabin). Anyway, the compound has cracked underneath where the mast is stepped and it looks like someone may have been messing with this area previously because of some missing / mickey mouse hardware.

Can anyone fill me in on what may be going on or may have happened and what types of repair and precautions need to be taken here.



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Old 26-11-2015, 21:11   #2
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Re: Deck under mast cracks.

From some angles it looks like foam. Does it feel like foam? Does it crumble like foam? What is the texture/hardness?

In the area that it has been cleared away to mount a bolt, is that how you found it or did you clear it away? Does it flake away in general? If so, could you remove a spot around one of the cracks?

Most importantly, perhaps: can you see any signs of cracking in the gelcoat on the cabin top in the same area?

It does look mickey mouse, perhaps in desperation to stop a leak they couldn't find?
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Old 26-11-2015, 21:26   #3
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Re: Deck under mast cracks.

Quote:
Originally Posted by Greenhand View Post
From some angles it looks like foam. Does it feel like foam? Does it crumble like foam? What is the texture/hardness?

In the area that it has been cleared away to mount a bolt, is that how you found it or did you clear it away? Does it flake away in general? If so, could you remove a spot around one of the cracks?

Most importantly, perhaps: can you see any signs of cracking in the gelcoat on the cabin top in the same area?

It does look mickey mouse, perhaps in desperation to stop a leak they couldn't find?
The compound is very hard and definitely not a foam, some type of epoxy I am guessing. The previous owner removed the headliner and I have not touched this area yet. I would be very hesitant to remove any of the compound at this point without some more idea into what might be going on first. I do not see any issues topside and the fiberglass above looks to be intact without fractures. I would be taking a wild guess that this is some type of compound being used to level deck transitions for the headliner to look better but the marks around the mast bolts make me want to believe that no backing plate was used (which sounds wrong to me) also, the position of the supporting poles top plate and size just appear to be wrong but I have zero experience about any of this so any advice is appreciated.
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Old 26-11-2015, 21:54   #4
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Re: Deck under mast cracks.

So those bolts with no backing plates, washers or nuts go through your mast, and this is how you found the boat?

And your compression post has bolt holes, but is just sitting there, being kept in place by gravity?

I suspect that the cracking you are seeing is due to the fact that this epoxy does not have any flexibility, while the fiberglass it is laid on does.

You need to identify what is on the other side of each of those bolts, in order to evaluate what needs to be done in each case. As you suspect, probably adding backing plates and hardware.

I would also repair or remove this epoxy, so that it doesn't continue to crack and peel behind any backing plate that you add in.

Finally (or first, really) I would try to find out if this compression post is original. Perhaps you can get more concrete advise at https://groups.yahoo.com/neo/groups/...tions/messages. It isn't very active, but there has been some discussion in the last month.

I'm not being very helpful, I am just bored tonight and your dilemma interests me.
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Old 27-11-2015, 08:57   #5
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Re: Deck under mast cracks.

engineering on that def looks dodgy! the plate at the end of the post is too small ( unless the mast base is 100% perfectly aligned with the post!) I'd expect that that base should typically have a surface area at least 4 times what you have. and some sort of backing block on top of that to spread load even further. there should be no core in that part of the deck that is compressible.
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Old 27-11-2015, 08:57   #6
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Re: Deck under mast cracks.

One way to determine if there is a problem is to check your turnbuckles. Yes, your turnbuckles on the side stays (shrouds). If the mast is sinking, which is what you are really concerned with, then the turnbuckles will be running out of threads when the rig is properly tuned.
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Old 27-11-2015, 09:05   #7
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Re: Deck under mast cracks.

Quote:
Originally Posted by BravoVita View Post
Under the mast in the cabin of my 1976 28' Sovereign CC, the fiberglass looks to have some type of white compound that was used at some point (not sure if it is original or not since it can be found in a lot of places mid cabin). Anyway, the compound has cracked underneath where the mast is stepped and it looks like someone may have been messing with this area previously because of some missing / mickey mouse hardware.

Can anyone fill me in on what may be going on or may have happened and what types of repair and precautions need to be taken here.
===

The material that is cracking looks like gel coat to me, or possibly some other polyester/epoxy like filler. Gel coat is brittle and cracks in similar fashion if stressed. The important thing in my mind is whether or not any leakage is taking place. If not, your basic structure is good and the fittings on deck are well bedded. If any of the on deck fittings are heavily loaded they should have either backing plates or over sized fender washers. Otherwise, assuming no leaks, you basically have a cosmetic issue.
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Old 27-11-2015, 09:16   #8
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Re: Deck under mast cracks.

All good info.. Anyone know of a solid rigging guy that can take a look and make some recommendations in the Palmetto FL area? This is not something I want to try and guess at.
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Old 27-11-2015, 09:25   #9
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Re: Deck under mast cracks.

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Originally Posted by BravoVita View Post
All good info.. Anyone know of a solid rigging guy that can take a look and make some recommendations in the Palmetto FL area? This is not something I want to try and guess at.
Most of this is really pretty easy to do.

1) you already know that either the mast base orthe post has been replaced because the bolts don't match up
2) someone put filler ( thats cracking off) on the underside. I'd remove it to see what it was "fixing"
3) take lots of measurements and pictures, then get the post out ( then the mast is off the boat) and have someone cut and weld it correctly. At the very least the top plate needs to be cut off and replaced with a top plate that is large enough to mate up with the bolts that we assume are protruding down from the mast step.

all doable without a "rigger"
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Old 27-11-2015, 09:25   #10
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Re: Deck under mast cracks.

The compression post is a column to support the vertical down forces from the mast & rig. It also is bolted at each end to prevent lifting of the deck. Lifting forces can happen as the vessel rolls to the sea but especially if your halyard turn blocks are anchored to the deck. If the deck is also balsa cored the flexing will let the core shear away from the glass. The repair you show may be a clumsy attempt to fix this.

I agree with the other's observations on the cracks. The hard epoxy is probably filled West system or other. Without glass or other strength element, it will be brittle and will crack as the deck flexes. You must stabilize the deck's motion - must be rigid. The neat resin should be removed. If any material is to be added/replaced, make sure you add glass cloth. You can glass overhead if you make up the patch on a layer consisting of: start at the bottom - stiff cardboard such as double layer corrugated, linear low density plastic release film is best (the white crinkly trash bags), glass layer. Mix the epoxy and apply with a throw-away brush so that the glass is wetted out. Apply also to the sanded, rouged prepared surface above. Lift the patch system into place. Use pre-cut struts of 1/2 x 1 strips as compression bows or larger stiff struts. Use a lot of these bows! You may want a few pieces of thin, flexible plywood on top to conform with the hull. Use heavy film on the deck below to collect the drips. When the epoxy cures the film will let you easily remove it and the cardboard. Can be done one-man but best with two.
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Old 27-11-2015, 09:58   #11
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Re: Deck under mast cracks.

My issue with assuming the white compound was a structural fix is two fold.. First, its everywhere mid cabin (see photo).. making me believe it was either original or used 10-15 years ago to level the fiberglass for a headliner. Two, the deck is solid, really hard and I can not find one imperfection in the fiberglass. Yes there could be something underneath but I would not want to remove any of the compound till I can understand what I am getting myself into before I start it.. For instance, it looks like the mast bolts are just freely turning so I assume the mast must be removed to properly mount the hardware (otherwise how would I be able to get to the bolt head). Can I put a temporary support up in place of the compression post to have it ready to reinstall once I can have the mast lifted. Again, I am just assuming and guessing so spending a few duckets to make sure something as simple as a little ole mast is attached correctly will not be something I need to shy away from.


(Can't get the img rotated for some reason)
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Old 27-11-2015, 10:47   #12
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Re: Deck under mast cracks.

Quote:
Originally Posted by pcmm View Post
engineering on that def looks dodgy! the plate at the end of the post is too small ( unless the mast base is 100% perfectly aligned with the post!) I'd expect that that base should typically have a surface area at least 4 times what you have. and some sort of backing block on top of that to spread load even further. there should be no core in that part of the deck that is compressible.
Well that is bogus advice. Between the deck stepped mast and the compression post is usually a bridge made of wood or metal embedded within the glass that spans about a foot to two feet either side of the mast. The mast itself usually is sitting on a metal flange that does nothing more than keeps the mast from slipping out of compression. Sounds like the bridge has rotted and needs to be cut out and redone with a new bridge. Fairly easy to do.

Folks usually screw up by over tightening their rigging, thus driving the mast into the boat. For cruising boats, a rig should not be tightened beyond the point where the stays can move horizontally about half inch at about six feet above deck. Racers usually over tighten for a race but then loosen up the rig afterwards.
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Old 27-11-2015, 11:33   #13
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Re: Deck under mast cracks.

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Originally Posted by reed1v View Post
Well that is bogus advice. Between the deck stepped mast and the compression post is usually a bridge made of wood or metal embedded within the glass that spans about a foot to two feet either side of the mast. The mast itself usually is sitting on a metal flange that does nothing more than keeps the mast from slipping out of compression. Sounds like the bridge has rotted and needs to be cut out and redone with a new bridge. Fairly easy to do.

Folks usually screw up by over tightening their rigging, thus driving the mast into the boat. For cruising boats, a rig should not be tightened beyond the point where the stays can move horizontally about half inch at about six feet above deck. Racers usually over tighten for a race but then loosen up the rig afterwards.

Dont see where the "Bogus" advice is there. If you look at the picture, the existing post and plate are far too small to even make a connection with the existing mast base. its not bolted in at all, just sitting there. the backing block ( usually something like G10) just helps with the irregular surface.

I agree people usually either over tighten or (alot more often) under tighten their rig. a Loos tension gauge is really the most accurate and repeatable way to tension your rig properly.
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Old 27-11-2015, 12:27   #14
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Re: Deck under mast cracks.

totally agree... from reading and observation, it seems to be that most people under-tension their rig for fear of 'breaking something' and it is actually the under-tensioning that puts significant strain on the rig and fittings in a seaway. The Loos gauge works well. The leeward shrouds should just start to sag in 10-12 knots. A 'half inch movement six feet above the deck' is so variable and unscientific as to be meaningless.
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Old 27-11-2015, 14:18   #15
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Re: Deck under mast cracks.

according my recent experience with my mizzen ,i agreed with RED1 aproach.In the old times ,the boat construccion were based in a sandwich composed by fiber-foam-fiber and sometimes an with an over tension of the stays together with the time and stress combined produced a reduction of the foam width and cracks in the gelcoat below the base Do you have some water accumulation around the base of the mast .This is a main sign of this effect .
Indeed is not possible extrapolated direct to your case because my boat is an old perry 47 .Regards
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