View Full Version : Mast Repair
04-30-2001, 01:19 PM
Oh the joys of Spring. I thought I was going to get off easy this year, but I discovered two fairly large projects. One of them is my mast.
The mast is 35 feet, hollow box construction, spruce, 30 years old. It has heavy blocking starting from about a foot and a half above the base and going up past the spreaders, with a channel cut in the blocking for the wires. (It's a heavy sucker.) The lower foot or so is only partially blocked, with a hollow portion in the center from the step up to the hole where the wires exit. The purpose of this hollow is to allow drainage. All of the glue joints from the bottom up to the wire exit hole have let go. The gooseneck, just above the wire hole, is of heavy bronze strapping and wraps around three sides of the mast. It appears to add significant strength and acts like a permanent clamp around the mast. Above that, the mast is sound and the joints are tight.
Upon discovery, I stripped the paint from the bottom three feet so I could inspect the condition of the wood. The wood was extremely wet under the paint. The blocking inside this portion of the mast was also wet. The original glue was resourcinal. There were two small soft spots on the surface, which I gouged out and will fill with epoxy. Fortunately, the weather has been very dry for the past week so the wood has dried out thoroughly.
I suspect the water got in through two places. The mast is stepped on a tabernacle and the drain hole at the bottom of the mast was too small and did not run free. I think water got into the wire exit hole and collected in the base. I also think that water wicked up through the end grain at the base when the water did not properly drain from the tabernacle. I do not think water got in through the outside, as the paint coating was sound and all fittings are properly bedded and fastened.
Here's how I plan to repair it. Clean the joints and faying surfaces as best I can using sandpaper, scraper, knives, etc. Soak all surfaces in CPES. To reach in to the hollow that runs about a foot and a half up the mast, I'll tie a small brush on to an extention handle and slosh it around up there as best I can. I'll use a syringe to squirt it into all of the joints and on all of the faying surfaces. I'll remove the fittings and apply it to the outside and into the fastener holes.
The next day, I'll glue it up using slow-cure epoxy thickened slightly with cabosil. I'll inject that liberally into the joints with a syringe. Clamp and let cure for a couple of days.
I don't want to use resourcinal because I can't be sure of getting tight fitting joints--and I'm not about to take the entire mast apart just to check. Also, I can't be sure of warm enough temperatures to get a good cure. Since I want to seal everything with CPES, I don't know if resourcinal will work on CPESed surfaces. I don't want to take the chance of failure.
My goal is to get stong glue joints and seal the wood in this part of the mast from water.
Anyone see anything wrong with this? Have any better ideas?
04-30-2001, 02:31 PM
Been there, done that, got the tee shirt...
My mast, a Cheoy Lee of similar construction, resorcinol glued, began to delaminate at about the same age. I ended up taking the whole thing apart, but it doesn't sound like you have as much of a problem. However... let's not jump to conclusions!
Your repair approach is the same I used and my mast has been up six or eight years now with not a single problem. (I did have a slight problem with the boom, but that was because I expected the epoxy to be stronger than the slight crook in the boom and the wood kept winning until I gave up and let her lay like she wanted.)
All I would add to your plan is to make damn sure the wood gets dried out well. That is obvious, I suppose. You won't get the epoxy sealer or adhesive to take hold otherwise. When I did mine, I cut up a bunch of finely tapered hardwood wedges out of scrap and VERY carefully started them in the cracks where the delamination occurred. By progressively tapping in the wedges, moving one ahead of the others, I was able to crack the glue line all the way up. (You may not need to go so far, of course.) When the seam was tenacious, I took a hacksaw blade in one of those single ended hacksaw blade holders and used it to saw the seam. This went pretty well when it was under tension from the wedges. The worst of it is getting the faying surfaces down to new wood. There's no point epoxying together two surfaces coated with already failed resorcinol or you are right back where you started from.
Your water problem is probably correctly diagnosed. I don't know how many times over the years I've seen masts pulled and opened (usually when the wiring comes out to renew) and watched the water pour out. It is really insidious, because it collects in a bunch at the bottom and then just evaporates and creates its own atmosphere in there like those terrariums we had in grade school, rotting from the inside. The only thing that saves a lot of masts is that there isn't much air in there after awhile and so the fungus has a harder time of it. The water could be coming in just about anywhere. Lots of times, it follows the wiring. Be sure you have "drip loops" where the wire exits the mast. You have to run the wire out and down, then U it back up again so the water running down the antenna and masthead light wires or whatever will fall off at the bottom of the loop. Even when the whole thing looks sealed up well, it can wick inside. Good thing you caught it when you did. BTW, I really don't think you should have a drain hole in mast, although it couldn't hurt. The object of the game is not to let the water get in there to begin with.
Look on the bright side, there's nothing you can't cure with a glob of googe!
06-06-2001, 11:50 AM
Have a similar challenge on my 50+ ft hollow box spruce mast. Resorcinol seam delaminating along the edge adjoining the wire winch for the main halyard.
The split has worked it's way from above the boom bracket to about 6 feet above the winch. Assuming this is largely due to the mechanical back and forth action of the winch since that is where it started.
Strategy is to work from a bosun's seat w/o pulling the stick.
Use fine wedges to open past the failure and clean to bare spruce.
Apply CPES with syringe to penetrate all seam surfaces.
Finally to apply West System thickened slightly w/ adhesive filler to completely fill the wedged open seam.
Remove wedges and clamp.
Opinions on any downside to working with the stick up?
Suggestions for good tools to use in trying to clean the seams within the confinement of what the wedges will allow?
Appreciate any insight.
06-06-2001, 11:59 AM
A word of caution on CPES: waiting to apply until after the pieces are glued is a good idea. I asked the manufacturer (Rot Doctor? Dr. Rot?)about this and they recommend gluing, whether it's resorcinol or epoxy, with bare, clean surfaces and applying CPES afterwards.
When you're re-gluing delaminated pieces, of course, it may not be this simple. Nothing's easy....
06-06-2001, 12:20 PM
Seth, good point. The rotdoctor says that if you use the tropical epoxy, you should CPES after, but if you use the layup epoxy you can CPES before. He doesn't say what to do if you use someone else's epoxy, like West System. If you're concerned, you should call Smith & Company directly. They can give you the best information.
I CPESed before gluing because the original joint failure was caused by waterlogged wood inside the mast. The only way I could seal it with any hope of not having a repeat failure was to apply the CPES before gluing. By the way, the Smith literature, at least as I remember it, does not say to glue first and CPES later. Am I wrong? Does anyone have the literature handy?
How would you get the joints separated enough to clean them out if the mast is stepped? I had a hard enough time getting the seams open when the mast was horizontal on horses. For seam cleaning I used a dental pick and a sharp putty knife to remove big clumps and flakes of loose glue; my Fein Multimaster with 60 or 80 grit paper where I could pry the seams open fairly wide; and sandpaper glued to one side of a stiff paint scraper where the seams were close and tight. I vacuumed the dust, wedged the seams open and let it dry for a week before applying the CPES.
06-06-2001, 03:41 PM
Vincem: get a bunch of pillows to land on in case the structure of the mast gives way. If you're far enough up, you could just ride it over into the water. http://media5.hypernet.com/~dick/ubb/eek.gif
06-06-2001, 05:04 PM
I wonder if much water gets in through the drain hole. I think I would put a cork attached to a leash in it so I wouldn't wonder anymore.
07-08-2001, 08:27 AM
Report on completed box beam delam project.
Ended up with more than 12 lineal feet of delam. Even with the mast stepped I was able to wedge open and pick out most of the resorcinol. Wherever it would not come loose I made judicious use of my old Makita 3 3/8" saw. Extremely thin kerf allowed me to take off only what I needed to.
Also finished the extreme ends of crack with that blade since wedging is not possible when you are adjoining the remaining good joint.
Cleaned joint thoroughly, scraped and sanded about 1/2" on either side to expose fresh spruce, and drenched with CPES from top to bottom, working from a ladder.
Gave the CPES 48 hours to cure and went back with wedges to open up seam and squirt West System w/ colloidal filler using a variety of syringes.
Working from just below the first spreader almost to the gooseneck, I was able, with one assistant mixing epoxy and filling syringes to wedge, fill, remove wedge about 2 feet at a time from top to bottom.
Barely had time when I reached the bottom to go back up and clamp everything thoroughly before the epoxy set-up.
This was done on a very hot humid day in full sun w/ standard catalyst, (not tropical).
Smith & Co. thought it was fine to prime w/ CPES before applying the West System incidentally.
Results: most satisfactory. The week following the repair we were caught with full main and genoa in a squall with 30+ knot winds. Mast looks like the day it was repaired.
Suggestions if you tackle mast delam like this either stepped or unstepped -
1. Don't shortcut the cure time for the CPES or premature set-up of the thick epoxy could result.
2. Insure that joint edges are not in contact after applying CPES as you remove the wedges.
3. Be prepared to work very quickly with the thickened epoxy - have extra of all tools and materials you think you will need on hand. You cannot begin clamping until you have injected the last bit of joint so if it begins going off before you finish - you're f*&^%.
4. The colloidal filler enhances the bonding which is already enhanced by the CPES, but is hard as hell to sand or scrape after cure. I went up and down the mast a few times when partially cured and carefully removed it with a sharp blade. Would not recommend release agents since they could get into the joint. Any other suggestions on this aspect of the repair?
The big stick comes down this fall for total renovation and surface treatment with CPES before varnish. The stuff is just plain magic.
07-08-2001, 08:19 PM
For a story right on point, go here.
07-08-2001, 10:03 PM
07-09-2001, 09:58 AM
Glad to hear you had good results. My repair has held up fine so far. I used MAS slow cure epoxy, so no problems with premature setup of the glue. I too thickened it with colloidal silica. To remove the drips, I used my Fein Multimaster with the scraper blade. The blade cut through the hardened epoxy fairly quickly and the shape of the blade allowed for good control. Then I sanded using the Multimaster with 80 grit. Finished sanding by hand and all was fair. I primed it with Sterling LPU primer and overcoated with Kirby's finest.
07-10-2001, 01:25 PM
I too am facing the regluing of my sitka spruce mast. It seems most everyone is regluing using epoxy. I believe it was originally glued with resorcinal which lasted a very long time. What are the advantages of using epoxy instead of resorcinal? I am a bit afraid of epoxy (for reasons of health and making a mess).
07-10-2001, 01:29 PM
With resorcinal, you need perfectly fitting joints and warm, dry weather. These are difficult conditions for a second rate woodbutcher (speaking for myself, only) to achieve for a mast repair done out of doors. Epoxy is much more forgiving. There's no reason to think that the epoxy won't last as long as the original resorcinal.
Powered by vBulletin® Version 4.2.1 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.