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  Q: How to repair stripped screw holes in hull?

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Author Topic:   Q: How to repair stripped screw holes in hull?
84 Montauk posted 07-06-2001 01:12 PM ET (US)   Profile for 84 Montauk  
After beating around this week towing teen-age "tubers", I noticed some loose screws in the stand-offs for the bow rail. I tried to tighten them, but they just spun. Any advice on the best way to repair this? Thanks.
Bigshot posted 07-06-2001 02:07 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Easy way is a toothpick or 2 stuffed in the hole. You can also fill the hole with epoxy and redrill. If it is the rail you are taliking about, try a wider screw and some locktite.
whalernut posted 07-06-2001 10:05 PM ET (US)     Profile for whalernut  Send Email to whalernut     
How about some wider screws and some 4200 or possibly 5200? Strong stuff. Regards-Jack Graner.
Hank posted 07-06-2001 10:42 PM ET (US)     Profile for Hank  Send Email to Hank     
For a quick fix I use a plastic screw anchor jammed in the hole. The best fix is probably epoxy and redrill as Bigshot mentioned.

Hank

Tom W Clark posted 07-07-2001 01:06 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
The above mentioned advice is, at best, "quick fix". For a truly satisfactory repair, you need to return the area the the screws go into back to their original condition.

Using an over size screw may provide some grip but the screw head will not sit down into the hardware and will stand proud snagging ever piece of clothing in sight.

You mention the standoffs for the bow rail. Are you talking about sheet metal screws driven into wood backing in the hull or are you referring to the machine screws that thread into the cast bronze backings that are fit from the outside of the hull? If the latter, then you could simply replace them.

To repair stripped screws into wood, jamming toothpicks or a plastic shield will work to a degree but what you really need to do is drill out the hole and epoxy in a wood plug. Note that I said "plug" not "dowel". The problem with dowels (or toothpicks, for that matter) is that the grain of the wood is aligned the wrong way. The threads of the screw will not be able to "nest" into the wood fibers and provide resistance to withdrawal. Installing dowels is a common mistake that sometimes works but the if the wood ever becomes wet the dowel and the surrounding wood will expand in different directions and at different rates.

For a screw hole repair on the bow rail, drill a 3/8 hole and use a 3/8 plug.

To install a plug you first need to cut a plug. You do this with a plug cutter and a drill press. If you do not have a drill press you can use a drill motor but you need to use a scrap of wood with a whole drilled through it equal in size to the outside diameter of the plug cutter, then use this scrap to stabilize the plug cutter and drill motor when you start the plug cutter into the wood from which you are cutting the plug.

In general the plug should be made from the same kind of wood as that which you are trying to repair. In the case of plugging the backing wood in a Whaler hull it's not so critical. I would use Mahogany or Luan if I had a scrap laying around or Douglas Fir, Hemlock, Larch, or some other strong soft wood. Hardwoods like Oak or Maple are not appropriate.

I use 5 minute epoxy for such repairs because I can get the job done in a few minutes, it's strong and waterproof. Go ahead and flush the wood plug out with the gel coat because the hardware will probably cover it.

If a repair is being made that will not be covered then fill it up flush and then route out the damaged area to a depth of about 1/32" -1/16" and fill with a gel coat patch paste.

This is a long winded response to a very small problem. The execution of the repair will actually take little more time than reading this post. Don't be afraid; do it right the first time and be done with it.

84 Montauk posted 07-09-2001 10:54 AM ET (US)     Profile for 84 Montauk    
Thanks for all the replies. I think I'll do the plug and epoxy fix mentioned by Tom W Clark.

Again, thanks very much. I'll update with my results.

Chesapeake posted 07-09-2001 12:12 PM ET (US)     Profile for Chesapeake  Send Email to Chesapeake     
Tom Clark: Is there a problem with drilling out the hole slightly and simply pouring in an "epoxy plug". Numerous posts have talked to this point. Am interested in your thoughts if you feel this is inappropriate.

BOB

Tom W Clark posted 07-09-2001 12:23 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Bob,

I think this is perfectly OK. The problem comes when re-drilling. The epoxy is harder than the wood so the drill bit will tend to wander off to the side. The best way to avoid this is to hold the hardware being attached in place and use a Vix-Bit, a self centering drill bit.

Bigshot posted 07-09-2001 01:54 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Depending on how stripped, put the epoxy in and screw the bolt in while wet. Will be tight, might be too tight but that is the point.
JimU posted 07-12-2001 03:03 PM ET (US)     Profile for JimU  Send Email to JimU     
If you follow Bigshot's advice coat the screw with automotive wax as a release agent. Once the epoxy sets up, you can back the screw out easily. Or, apply a little heat to the screw head with an electric soldering iron. That will unstick if you don't apply a release agent.
Bigshot posted 07-12-2001 03:08 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
good idea!
lhg posted 07-12-2001 06:48 PM ET (US)     Profile for lhg    
I think white Marine-Tex is just as good, and MUCH easier to use than liquid epoxy. It mixes up like putty, and is easy to use and pack into the hole. Sets up in 4 hours. It will bond to both the skin and wood backer pad. No heat problem in curing. If the hole is covered by the fitting, you don't even need to re-gelcoat. Just sand and buff flush, center punch the hole, and redrill. The old hole should be drilled out twice the diameter of the previous screw, similarly to the way TWC recommended a 3/8" plug. (these, incidentally, are available pre-cut at West Marine, all diameters, in both mahogany and teak)
JBCornwell posted 09-08-2001 11:18 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Tom Clarks fix works well, but can be improved on: Instead of making wood plugs of 3/8", make 1/2" plugs of WhaleBoard (currently used by BW as a replacement for wood backing). This material lends itself to tapping for machine screws and holds as well as metal. Drill and tap for #12 machine screws. A little silicone and you will nevere have a problem with that attachment again.

Good luck.

Red sky at night. . .
JB :)

gunnelgrabber posted 09-09-2001 01:36 PM ET (US)     Profile for gunnelgrabber  Send Email to gunnelgrabber     
to tom clark,..thanks for the above information...i am curious to know why you say oak or maple isn't suitable for that purpose?..(granted ,whalerboard or epoxies etc. might do better than any real wood.)thank you...lm
Tom W Clark posted 09-09-2001 02:59 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
gunnelgrabber,

The idea is to return the backing wood to its original condition. Before synthetics, Whaler used plywood which is relatively soft and easy to dive a screw into. Oak or maple is quite hard. If you plug an old hole with a hard wood the danger is twofold:

1) the hardwood plug will tend to split easier than a softwood plug:

2) the screw going back into the original hole (and the new plug) will probably not be perfectly centered on the plug and the screw will tend to "seek" the softer plywood and possibly "drift" away from where you really want it.

gunnelgrabber posted 09-10-2001 05:35 AM ET (US)     Profile for gunnelgrabber  Send Email to gunnelgrabber     
to tom clark,...thank you, that makes sense....lm
Soho posted 09-10-2001 08:22 AM ET (US)     Profile for Soho  Send Email to Soho     
While I have looked at "Starboard" at West Marine, I have not actually used it or Whalerboard before; does WEST system epoxy adhere to it ? I would not think that it would, but of course I have been wrong so many times before !

Thanks,

Ron

Chesapeake posted 09-10-2001 03:53 PM ET (US)     Profile for Chesapeake  Send Email to Chesapeake     
Soho: That is a great question. I also would like to know the answer. When you machine it, it has a very slick, hard surface that would seem to hinder adherence to epoxy - BUT I've never tried it...

As far as the difference between West Epoxy and Marine Tex, it is likely personal preference. After having used both, I prefer to use epoxy. The syringes you can buy at your West Epoxy dealer are absolutely perfect for cleanly injecting moderately thickened epoxy into small screw holes.

These syringes may work equally well with Marine-tex, if you really prefer that over West. Cannot say I have tried that either.

What I really like about the West system is its versatility. I always have a quart (along with small hardener) with the pumps on hand in my shop for projects, both boat and home. I've used it to soak the bottom 2 feet of wallboard in a garage that tended not to drain water very well. It's great with a little thickener to bond anything that is going to get outdoor use - wood planters, for example. As for the boat, all joint on wooden seats and consoles, filling voids, bonding, filleting repairs etc... every bit, at least on my boat was very well accomplished with West Epoxy and one or more of their additives.

Yep, I'm sold. Do you think I could get an endorsement contract?

Bob

Chesapeake posted 09-10-2001 03:53 PM ET (US)     Profile for Chesapeake  Send Email to Chesapeake     
Soho: That is a great question. I also would like to know the answer. When you machine it, it has a very slick, hard surface that would seem to hinder adherence to epoxy - BUT I've never tried it...

As far as the difference between West Epoxy and Marine Tex, it is likely personal preference. After having used both, I prefer to use epoxy. The syringes you can buy at your West Epoxy dealer are absolutely perfect for cleanly injecting moderately thickened epoxy into small screw holes.

These syringes may work equally well with Marine-tex, if you really prefer that over West. Cannot say I have tried that either.

What I really like about the West system is its versatility. I always have a quart (along with small hardener) with the pumps on hand in my shop for projects, both boat and home. I've used it to soak the bottom 2 feet of wallboard in a garage that tended not to drain water very well. It's great with a little thickener to bond anything that is going to get outdoor use - wood planters, for example. As for the boat, all joint on wooden seats and consoles, filling voids, bonding, filleting repairs etc... every bit, at least on my boat was very well accomplished with West Epoxy and one or more of their additives.

Yep, I'm sold. Do you think I could get an endorsement contract?

Bob

salty_dawg2 posted 09-12-2001 12:00 PM ET (US)     Profile for salty_dawg2  Send Email to salty_dawg2     
I read a recent post somewhere that mentioned using "PAM" (the kitchen spray stuff)on the screws before seating in West System epoxy to make them removable in the future. This was per a rep from the makers of West System.
tully_mars posted 11-14-2002 09:46 AM ET (US)     Profile for tully_mars  Send Email to tully_mars     
Ok, I still have a question regarding the above procedures. I have two backing plates (2 on each side) on the outside of my 1972 16' hull, what are the exact screw sizes I need to reach them? When I took the bow rail off it had 1" #10 screws, but none were tight and didn't seem long enough to get into the metal plate.

I just had the boat Imroned, so not to excited about the plug fix (yes, should have done it before hand). How about the marine tex fill and redrill? Bigshot, how has your luck been with that?

Tully Mars

David Jenkins posted 11-14-2002 03:25 PM ET (US)     Profile for David Jenkins  Send Email to David Jenkins     
JB, could you or someone else explain what you mean by "Drill and tap for #12 machine screws." I have never "tapped" for a screw and do not know what that means. Also, are you saying that you recommend using machine screws regardless of the substance used, or are you saying that when using Whaleboard only machine screws should be used?
newt posted 11-14-2002 04:31 PM ET (US)     Profile for newt  Send Email to newt     
David, to tap a hole is to create threads in the hole so you can screw in a bolt, machine screw, etc. You can buy individual taps or a tap and die set (a die is for creating threads on a bolt, screw, etc, or for repairing damaged threads on a bolt screw etc)

JB's procedure is to epoxy a plug into the foam/hull/whatever, then drill the appropriate size hole in the plug, then screw the tap into the hole. Once you have done all that, you can actually screw a machine screw in to the plug - kinda like having a nut epoxied in.

weekendwarrior posted 11-15-2002 04:46 PM ET (US)     Profile for weekendwarrior  Send Email to weekendwarrior     
Tapping means to run a "tap" into the hole which will cut threads for a screw.

I've got the same problem with 3 or 4 screws in my rail which were like this when I got the boat. I was thinking of using marine tex (love that stuff!) and a syringe to fill the holes and then drill and put the screw back in. Does anyone see a problem with doing it this way?

Jerry Townsend posted 11-15-2002 06:16 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Often, I don't have the time to make a plug (Tom Clark's comments regarding the grain are right on!) and then take an alternative method - of thoroughly mixing a little saw-dust into a 5 minute epoxy mix. Fast, tempers the hardness of the straight epoxy a bit, drills and accepts screws easily and is harder and will hold better than the wood by itself. ---- Jerry/Idaho
David Jenkins posted 11-15-2002 08:42 PM ET (US)     Profile for David Jenkins  Send Email to David Jenkins     
So, is it always preferable to run a tap into the hole and use a machine screw, or is this method only ideal with Whaleboard? Are wood screws only used on a Whaler when people don't have time to make a repair the right way?
Tom W Clark posted 11-15-2002 09:34 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
David Jenkins,

Use a machine screw if the material you are screwing into is capable of supporting a tapped thread. You would not use a machine screw with plywood (or solid wood) backing. You would use a machine screw with aluminum and could use one with whaleboard or an epoxy insert.

For attaching to wood backing in Whalers, you want to use a sheet metal screw, not a wood screw. A sheet metal screw has a constant diameter shank and is fully threaded whereas a wood screw has a tapered shank and is partially threaded.

Back out just about any screw out of a classic Whaler hull and you will find a sheet metal screw unless it is a screw used to attach the base of the center stanchion of the bow rail on a 16' 7" hull (I'm unsure about the 13' and 15' hulls), in which case it wil be a machine screw tapped into the imbedded aluminum plate that is placed there for this purpose when the hull was built.

David Jenkins posted 11-16-2002 12:22 PM ET (US)     Profile for David Jenkins  Send Email to David Jenkins     
Thanks, Tom. To summaraize, when going into metal (aluminum or stainless) or when going into whaleboard or an epoxy insert, tap the thread and use a machine screw. When going into plywood (or a solid wood backing), tapping is not necessary but I should use a sheet metal screw. Right?
tully_mars posted 11-16-2002 11:09 PM ET (US)     Profile for tully_mars  Send Email to tully_mars     
BTW, all, don't forget but what is the length/size of the machine screw that goes into the metal backing plates on the bow rail? Thanks

Tully Mars

tully_mars posted 11-17-2002 09:46 PM ET (US)     Profile for tully_mars  Send Email to tully_mars     
After some experimenting, the screws to reach the metal plates on the side of the hull for the bow rail or #10, 1 3/4". The very front stand I am not sure of yet, got to get some more screws.

Tully Mars

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