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Rotten core around Mast Step-repair

25K views 52 replies 11 participants last post by  superiorvoyager 
#1 ·
When I bought my 32'Voyager 4 years ago it had a slight leak at the Mast step. I caulked the Bolts and it seemed to fix the problem but it turns out all it did was keep the water from coming through the bolt holes in the inner skin and the water just pooled inside and rotted out all around the Mast step causing the step to start depressing the deck. I took the mast down this fall with the intention of doing repair in the spring but discovered that the core had totally rotted out for a good foot around the step (maybe more as I haven't opened it up yet but the Fiberglass skin at the front of the step had cracked and you can see in and there is no wood left there. I've read lots of posts here about replacing the core but have had a number of people including one boatyard suggest instead of replacing the Balsa Core with the same to remove the old core and make that area solid fiberglass/West System. My father had a boat repair place repair the deck on his old boat a number of years ago and this is how they did it and it did seem to hold up well. Obviously the weight would be greater but what other disadvantages would there be? Has anyone done this?
 
#2 ·
I can't think of any disadvantages, other than the one you mentioned, to making the area solid and eliminating the rot problem completely.
You could even lay up a 1/4" plate of aluminum to make it easier to attach deck hardware in the future.

I've had a couple of customers that have had this problem. One, whose boat was quite old and well used and who wasn't really concerned about trying to make the area look perfect, I was able to help.
The other one, I just referred to a good fiberglass guy. He had major problems all over his deck and was way beyond what I wanted to tackle. .
 
#3 ·
I must have read the OP wrong, but it sounded like there's balsa core between the mast step and the compression post ?

Balsa core is awful for compression loading. The only production sailboats I've done have been either ply(partners for keel stepped) or solid wood core (deck stepped).

Is this standard practice in production sailboats ?
 
#4 ·
Just did it...soild is the way to go.
 
#5 ·
It is Deck Stepped and as Far as I know it is Balsa. There is nothing left in that area to be able to tell but the report that I had from the Yard that Built it said the Deck is Balsa Core and didn't indicate that there was a different core in the area of the Step. Either way it has to be replaced as it has totally roted out. Don't know yet how far I will have to cut it back though.
 
#7 ·
Though solid glass will fix problem,it's probably not best choice unless you have fiberglass experience.Check West System tech site for detailed help.I like Coosa structural foam as core material....1/4 aluminum plate for additional stiffness and thru-fastening is also a great idea. Try to make repair area symetrical,with rounded edges and at least several inches into sound existing core.Don't forget to shim deck to proper position before layup!
 
#8 ·
Tip #1
If your deck surface is not damaged do all your work from underneath...that way your head liner covers your work and you don't have to have a perfect finish.

Tip #2
Use the tacky resin that they use for hull overhang repairs..for all your overhead glass work...I forget what its called.

Tip #3
Use a chunk of 1" or 3/4" iron pipe with a threaded collar as your jacking system..simple, cheap, cant move...get real fancy and have the coupler in the middel of two pieces.

Tip #4
Beg, barrow or rent a good respirator, buy a pair or two of those white throw away coveralls and a whole box of single use latex gloves...you will want a good small shop vac and a ton of cardboard and a big roll of that 2' wide blue painters tape to protect your boats interior...borrow or buy a cheap 500 watt halogen work lamp.

Fiberglass is an art but its not rocket science..experiment with two or three different ratios of catalyst to see what work time and heat you get..also pay attention to the kick so you learn when to stop messing with it and avoid ruining your cloth layup. Don't go for anymore then 3 layers in one day...it could overheat and turn black on you.

Tip #5
Stop in at some boat yard/ glass shop and see if you and chum up to a glass guy with an offer of rum and beer to help you out.

Good luck.
 
#9 ·
to answers, "SOlid is the way to go" and "it's probably not the best choice" what are your reasons. As far as experience I have a lot of experience with fiberglass (west system) over the years (boat and car repair, canoe construction built a 16' glass over wood boat years ago etc.) I also have a lot of experience with wood (finishing carpenter, fine furniture and Luthier). one problem with wood is If I am going to use Balsa or Coosa I'll have to order it in where as I have everything I need for west system
 
#13 · (Edited)
to answers, "SOlid is the way to go" and "it's probably not the best choice" what are your reasons. As far as experience I have a lot of experience with fiberglass (west system) over the years (boat and car repair, canoe construction built a 16' glass over wood boat years ago etc.) I also have a lot of experience with wood (finishing carpenter, fine furniture and Luthier). one problem with wood is If I am going to use Balsa or Coosa I'll have to order it in where as I have everything I need for west system
It would help if you quoted your intended target... I had to go searching as to whom you were asking .

IMHO... The only reason it was not soil to begin with in your and my boats is the builder was to cheep to do it..A lot of top of the line boats have a sold core where intended deck penetrations are..cheaper built bots not so much.

You ask why...Simply water intrusion ....intrusion and compromise of the core material rather wood or foam that you are currently facing and would not and will not ever be a future issue with solid glass core in that area.
a
The only reason for any plywood or balsa core in the first place was for a stiffner..and cheap stiffening at that...There is an exception when an insulating factor is desired in the hulls construction..but a modern sandwich is ultra light and ultra strong..but still generally solid glass where penetrations are engineered to go through either their decks or hull.

I have no clue as to why it was suggested as a bad idea to go solid in your mast step area..maybe he will respond to his answer.

FWIW...repairing it from the top will be WAY easier..just way harder to get your top gel-coat looking factory nice that's all..as you will have gravity working for you not against you...as I said earlier practice with 2 or three goes at mixing and saturating some scrap pieces together to get the hang of saturating and working with mat and resin..it ain't rocket science..learn to work all the air and excess resin out of the mat..gobbing on way to much resin is a beginners fist mistake..you dont want any unsaturated areas but you dont want it swimming in the stuff either..it will be brittle and crack.

You say you have lots of experiance with glass...Then Go For it!..If I was there I would help you.
 
#11 ·
Personally I'd stick with marine ply under a deck stepped mast. Were it my own job, I'd probably run one piece the thickness of the core to replace the balsa with a generous lap, say two or three times the area of the actual step. Another piece of 3/4, cut to the shape of the step with the edges chamfered would provide a pedestal of sorts to avoid the potential for water to find its way in.

Again, it's your project so it's your call, but balsa isn't commonly used in area where there's point loading like under cleats and winches but is 'fine' in areas where the entire panel is loaded (like side decks, cockpit seats, etc)
 
#12 · (Edited)
So even if I go with wood don"t use balsa but use marine plywood. But what is it's advantage over fiberglass? I should mention that I will go in from the top since the deck requires repair where the outer skin cracked due to the compression. As far as the sugestion of stopping into a boat yard or Fiberglass place there are none here. There is a boat yard 140 km away but they don't do this type of repair anyway.
 
#14 ·
I'd go solid not wood core of any kind under the mast. Stillraining is right - the only reason builders use plywood is that it is cheaper and is also faster than multiple layers of glass. I'd use epoxy (West as I know it well) and rather than mat and cloth or roving I'd use 1708 biaxial - stitched as opposed to woven roving with mat already attached to one side. It's easier to use and fully compatible with epoxy - some mat isn't epoxy compatible. If your deck is already needing repair going from the top is always the best way - it's easier and the job will turn out better. I'd paint after instead of gelcoat. For a good rundown of this see Tim Lackey's site - Northern Yacht Restoration | Tim Lackey: One Man, One Boat at a Time. He recores decks on a regular basis in his restoration business and documents everything with lots of pics. Just click on one of his projects and follow it along.
Hope this helps.
Brian
 
#15 ·
try this....?

I've done this before. If there is only a 1 ft area use stiff wire to dig out all rot wood. Attach vacuum to small tube to help. Get west sys epoxy in a empty caulk tube and attach small tube to end of caulk tube end. Stick tube in access hole and pump away. Don't peel away cabintop. Unless U R a fbgls pro it will never look right
 
#16 ·
I think gwp is wrong. The area is over 1 square foot. That's a large area to fill with epoxy that way. Besides, there is little strength to epoxy without fibreglass imbedded in it. And this will be under a mast so it requires strength. You will have to paint, but it's easy to get a fair surface. Just build it up layer by layer (1708 biaxial is about 1/8" per layer I think) and when you are almost level with the deck surface, sand and squeegie a fairing coat of epoxy mixed with fairing filler (West #407). sand and refill any low spots with fairing again until there are no more low spots. Sand lightly and finish with a coat of straight epoxy put on smoothly. Then prepare for the paint you choose. It isn't hard to do it just takes a bit of time. If you can read instructions you can accomplish this.
Brian
 
#17 ·
I suggested you replace with core material so that deck structure with similar qualities of stiffness and flexibility as originally designed can be maitained.Also,a heavy,solid lay-up can be difficult to fair without removing glass again. Since it is mast step area,all epoxy and 17 oz. material will definitely do the job-I missed the size and type of boat-just be aware if cabin top is lightly built and supposed to give a bit ,it probably won't anymore
 
#19 ·
mitiempo said:
the only reason builders use plywood is that it is cheaper and is also faster than multiple layers of glass
Respectfully Brian, I think you're forgetting about about the intent of laminate construction being to provide two skins held at a fixed distance apart to provide MORE panel stiffness than the same amount of material as a single skin. The key to that stiffness lies in the compression strength of the core.
Also, it's not faster...it adds time because it has to be added as it's own step which disrupts the layup timing. Then it has to be flood-coated before the inner lams start going on.

Another take on gwp's suggestion: remember here that the OP wants to use West System because that's what he's got (or what he's most familiar with). Ignoring the cost of filling 1/2" void left by the core, the exotherm will at least cause the glass to print through the gel and will at worst cook the gel, permanently discoloring it.

With that in mind, the exotherm will also make a solid casting a tricky job for someone who is fairly new to it. While they add a ton of strength, fibers don't do much to dissipate the heat. Remember that the heat vs cure curve for epoxy is much different that poly based resins.

Also, given the temps he's likely to see over the next while, he will NOT get a sufficient cure to re-step the mast, re-rig, and sail the boat anytime soon. Personally, I wouldn't feel comfortable restepping the mast on a solid epoxy layup that hadn't progressed very far beyond initial cure. I think it's important to point out as well that the exotherm enables the initial cure. Sure, it may feel hard, but only time can fully cure epoxy.

I can't really think of any issues with a solid layup of epoxy and cloth, again as long as the exotherm is dealt with. A continuous layup (always adding the next layer while the previous is cool but still green) will give all the units a primary bond but should allow the heat to dissipate. Once you compare the added cost to the properties gained, I'd still go with plywood core.
Just different strokes I guess.

Plywood has more compression strength than solid wood in this application unless he wants to cut short pieces and use the endgrain similar to the way a butcher block is made (and the way the balsa is laid).

Plywood has more panel strength than solid wood, so will do a much better job of spreading the loading evenly all around the step. THAT is the primary reason it's used in decks and steps, where balsa is used in cabin sides and coamings. Core materials are an insignificant proportional cost in any well-found production boat. Balsa is easier (read:quicker) to work and lighter than ply.

Again, this is just what my experience has shown me, for right or wrong.
:D
 
#20 ·
I doubt that Hinckley, Morris or other premium builders put ply under the mast step. Cost really isn't a factor for these builders - quality is. I suggested using multiple layers of biax. Not all at once. Even if you wait until one layer is hard it's easy to wash the amine off with a nylon pad and some water. Exotherm is not an issue if done this way. West epoxy is usable down to 35 degrees f. At these cold temps exotherm is less of an issue. Plywood does have more compression strength than solid wood - of the same species. Fir or mahogany plywood still compresses and under a mast fully rigged it will eventually happen. If any moisture gets in it will deteriorate and that's where we started. As far as core material where core should be used, balsa is far superior in several ways than plywood. Less chance of moisture travelling with end grain balsa, less weight with balsa where the weight is not an advantage, and better bonding to curved surfaces with balsa than with plywood. The following is taken from West's fibreglass repair manual which is free on line here.http://westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf
Brian
 

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#22 ·
Yes plywood could be used - the original builder did. But solid epoxy and fibreglass is I think the ultimate solution. Never again will it compress or absorb water as has happened to get us here. If the plywood is adhered properly and coated in epoxy totally it would work. I think it would take almost as long and be almost as expensive to do this with plywood as with biaxial and epoxy all the way through. The fairing, prepping for paint, and painting will take the longest - and you have to do this with plywood as well as all epoxy and glass. I think the goal is to fix it better than new, not necessarily copy what the builder did.
Brian
 
#23 ·
Im sorry but i have been watching this and have wanted to ask this but was afraid of sticking my nose where it was not wanted...

Has any one ever thought of a using vacuum bag process and building a carbon fiber step assm and bonding it in? The best of both worlds, strong, light and tough as hell. I have made some rather complicated and large items in this manner.
A vac-bag step assm will be so compressed that air can not penetrate much less water .
 
#24 ·
Please stick your nose in...In short my answer is yes ,but with galss not CF.

Please walk us through the process on the cheap so to speak.
 
#25 ·
Wow, the process is simple enough.
You build a rudimentary mold to make a part, figure out size shape and how you are going to mount, said part. Calculate how much strength you will want lay the carbon mat then pour in the resin.
slip a special bad over it and draw a vacuum with either an ac type vac pump or even a hand held brake bleeder pump.
The resin will cure in a vacuum and all the air in the structure will be drawn out. Leaving a VERY strong object. The Vacuum has the effect of drawing the layers very very tight.

2 layers of weave and a thin resin leave behind an extremely strong but quite thin part that is air and cavity free. I buy a bunch of stuff from a company called Max Bond while i am not here to push any product they do have a very good 4 min video on vac-bag process on a very low budget.

You will have to wade through the sales pitch but read up on the process and it will show one in action..
CARBON FIBER FABRIC 3K 2X2 TWILL WEAVE 6 OUNCE 50" WIDE - eBay (item 220500561712 end time Nov-24-09 16:02:23 PST)
 
#26 ·
Ah, gotcha ...different train of thought...I was thinking more in place as in overhead vacuum techniques to suck everything up defying gravity so to speak.
 
#27 ·
While there would be a few challenges but if there we a hatch to got on both sides of it..... It could be done!
Super strong and air free.. Rather than pile on the glass and resin you could use Styrofoam as a filler or supports. As funny as that founds all F-1 cars use Styrofoam much in the way boat builders used balsa wood.
It could be done, i wish i were closer to this guy, we could do a few tests to see but i dont see why not.
 
#28 · (Edited)
Hmmm...there again though your entering in a compressabal elliment where you do not want one...I would just like a quick clean way to vac any weard inplace profile with solid glass build up myself.

As an example..I would not mind adding 1/4" of roving or bi-directional to my whole hull...but adhering such a large area with quality is tough to do .
 
#29 ·
For the record, I can't think of any application in a boat where you would use plywood without glassing over it, even if it's just a single unit of 6oz to protect the epoxy barrier from abrasion like you see in plywood boats. In this application, the plywood provides an inexpensive core material to space the two laminates apart without any significant compressibility within the core material.

I haven't worked much with carbon, so I have a couple questions myself.
Would the weight savings be worth the cost of the material for this application ? I can see it if that's how the rest of the boat is built, but as a retro on an admittedly-inexpensive boat it seems like money better spent elsewhere.
What would be the advantage of carbon in this application ?

Dieselboy, if by 'Styrofoam' you mean blue- and pink-board, I gotta disagree with you. Yes it's used for body panels in many custom vehicles, but only where an inexpensive material is needed to hold shape. Using it as coring in a structural panel cause it to fail in long cracks that subject the glass to wicked shearing forces along a sharp line in the same place on the inner and outer laminates. If you can point me to a true unibody (structural) application that uses it for coring I'll happily stand corrected because it'll give me a lot more options in my own work once I figure out how they get the resin to saturate it...

mitiempo said:
Yes plywood could be used - the original builder did.
According to the OP, it was the fact that balsa core and NOT plywood was used for core that got him here. There are many (most?) production boats out there with plywood that never gives a worry as long as it's encapsulated. Plywood coring just doesn't fail without help - either through water ingress or mechanical damage.
 
#31 ·
. There are many (most?) production boats out there with plywood that never gives a worry as long as it's encapsulated. Plywood coring just doesn't fail without help - either through water ingress or mechanical damage.
Yes this is a very factual statement.

All a couple of us are trying to stress is that when you have a penetration into that core material you now have created a path for water ingress.

There are a couple ways to prevent this at construction but which are seldom used by the cheaper builders...One is as several have mentioned a solid glass core in those areas..or secondly over drilling the diameter of the area by 1/2" or more, sealing the core edges with penetrating epoxies then filling that area with thickened epoxy..next you re drill through your solid cored area to the desired bolt size needed. This takes more time then building it that way in the first place but has the benefit in exact placement for the mounted hardware.

Nothing wrong with building a large area back to the original way it was using plywood or whatever core material you prefer..but as long as you have it open why not use say a 2" hole saw or cut out a larger area for say a mast step with a saber saw in your known deck penetration areas and make those solid..it would only take a few minutes longer to glass up solid. The problem is cured forever. That's all were saying..to each his own though.

Carry on!
 
#30 ·
If the original builder used balsa under a mast it was a mistake. The force downward of a mast rigged on a boat will guarantee a failure if this is (was) the case. Plywood is a step better but still compressable over time and when the compression occurs there will inevitably be at least hairline cracking that will allow water in. The water will cause rot because even if the plywood is sealed it will lose the integrity of that seal when enough force is applied to it (tight rigging trying to force the mast downward not to mention the sailing loads). If you're in a colder climate there is the freeze/thaw cycles which are guaranteed to open any hairline cracks further over time. If the skins were thick enough to prevent this over time there would probably have been no reason to use the plywood to start with as the skins would not in any way be in need of a core. Many boats by many builders were built this way and they are having problems 20, 30, or 40 years on. Cores work well if they are kept dry and not crushed by large forces. I don't believe that this is good engineering for all time, just for a while. As to carbon - it would be a waste of money in this case as it's only purpose really is to save weight - a square foot of glass/epoxy 3/8" or 1/2" thick can't weigh more than 5 or 6 lbs. The mast step doesn't have to be super strong on its own - just be non-compressable to transfer the force to the bulkhead or compression post below.
I don't believe that F-1 cars are built with styrofoam - in the crash testing videos I have seen it looked like a carbon fibre laminate without foam.
Brian
 
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