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Pocket screws in boat building?

4K views 21 replies 11 participants last post by  poopdeckpappy 
#1 ·
I asked this on the wooden boat forum too! ( I'm living on the edge! )

Would you use them?

what are the pros and cons of using them?

Would the use of pocket screws be totally immoral?? :D

then the question is are the screws available in SS or Brnz?

Think I'll look around for my flak jacket! :eek:
 
#2 ·
I'd be concerned about screws being the only thing holding stuff together. Glue - resorcinol or epoxy- would seem to be indicated as well. Steel screws will leave quickly start to leave rust marks. The butt joint used in the pocket screw technique may work well in dry, on-land situations. I wonder how well it would hold up to constant moisture and the attendant swelling and warping of marine situations. The pockets might be a site for rot to begin forming too, unless they were filled in with a putty or compound of some sort. You try it first, and let us know how it holds up!
 
#3 ·
I asked this on the wooden boat forum too! ( I'm living on the edge! )

Would you use them?

Yes

what are the pros and cons of using them?

pros;
they're strong, fairly simple jig, eliminates clamping ( except for maybe alignment clamps )

cons;
not very attractive even with plug, so keep out of line of sight

Would the use of pocket screws be totally immoral?? :D

No

then the question is are the screws available in SS or Brnz?

maybe, but they do have non corrosive PH fasteners

Think I'll look around for my flak jacket! :eek:
.............
 
#4 ·
In addition to the potential rot paulk mentions, the pockets remove material and create weak areas in the wood.
Most broken items I've seen that were built with pocket screws, have failures where the pockets were.

Filling the pocket with tight fitting glued in dowels -may- approach the strength of the original material, but I wouldn't want to rely on it.

Pockets are fine for tables, interior furnishings and any non-critical assemblies. But for anything else the potential risks are too high.
When you consider the added time required to use pocket screws, there is no advantage. Glue or ring shank nails will have far more holding power.


Ken.
 
#5 ·
In addition to the potential rot paulk mentions, the pockets remove material and create weak areas in the wood.
Most broken items I've seen that were built with pocket screws, have failures where the pockets were.
When done correctly, using correct pocket depth and properly size PH fastener, (along with some gorilla glue} this is not a issue

Filling the pocket with tight fitting glued in dowels -may- approach the strength of the original material, but I wouldn't want to rely on it.
again, not really an issue, but I would use the pocket plug anyhow, you can get them in most all species

Pockets are fine for tables, interior furnishings and any non-critical assemblies. But for anything else the potential risks are too high.
I was thinking this is what deniseO30 was talking about

When you consider the added time required to use pocket screws, there is no advantage. Glue or ring shank nails will have far more holding power.

Ken.
the time envolved using a PH jig is minute and the advantage over glue and ringshank is enormous, a nail, any nail work by forcing aside material and relying on friction as material compresses back around the nail to hold.

A pocket hole, you're using a stepped bit that creates not only the pocket but also a shoulder, then continues with a pilot hole into the joining material, the pilot hole is smaller dia than the PH screw which is self drilling and only threaded about a 3rd of the screw shank, the remaining shank is smooth.

If done correctly you end up with a clamping force between the screw head sitting on the shouldered pocket and the screw thread that has pass completely though the pocketed stock into the joining material.

This in addition to a good wood binder is very strong
 
#6 ·
I don't see why you couldn't use them for pieces like tables and such. I wouldn't recommend using them for bulkheads and other structural pieces.

Ideally, if you could find them in Magnesium Bronze or 316 Stainless, you'd be best off using them, but even normal steel would work, provided you sealed the wood properly and took steps to prevent the fasteners from getting wet.

However, I wouldn't use pocket screws to fasten laminated materials together, at least I wouldn't recommend putting pockets into laminated materials—like marine plywood—since I think the pockets are better suited to solid wood. For instance, you could use pocket screws to fasten a marine plywood top to a hardwood table base, provided the table base had the pockets in it, not the top.
 
#9 ·
#8 ·
there is a company that makes the screws in ss and brnz. I don't see them in any part of a boat below the water line but the clamping type of use they provide is pretty hard to ignore, IF the hole or plugged hole is not visable.

I'm going to use them to set up the forms for my next building project. a 11 or 12 rowing dingy. Cabinetry seems to be the best way to use pocket screws.

I thought this would be a fun and thought provoking thread! ;)
 
#10 ·
So it "toe-nailing" with a self tapping screw!

It looks to have a raised thread like a drywall screw.

It seems to be less about the design of the screw, and more about the jig that makes it easy to drill the counter sink hole.

I would think the question about using this to attach bulk heads would be more about using this method than this particular screw.

As for me those screws have no place on a boat...the idea of "toe-nailing" has its place...if used for attaching bulk heads I'd us a lot of screws, SS or bronze.
However, I would prefer other more robust methods that will be easier to plug the holes.
 
#11 ·
I don't believe she is talking about using it for structural items, like bulkheads... Denise is smarter than that. I believe she may be intending to make a table or other furnishings for her boat with pocket screws. There should be no problem with doing that IMHO.
 
#13 ·
In certain applications pocket screws are superior to biscuits. I agree it is more about the pocket itself and the application of use rather than the actual screw. If the SS pocket screws were way expensive I would just use a similar sized SS pan head screw.
 
#15 ·
There are lots of woodworking joints because there are lots of applications. I like the Kreg setup for cabinet work. Once you're used to their jigs you can go pretty fast.

Biscuit joints, especially if you use two offset biscuits are surprisingly strong. But it all depends on what you're trying to do, what kind of wood you're using and what kind of environment it will live in.

Fine Woodworking did a stress test of woodworking joints a while back. You can find it on their web sites as a PDF. The results are pretty interesting if you enjoy wood butchering. taunton.com/finewoodworking/ToolGuide/ToolGuidePDF.aspx?id=31926

I say use whatever tool / joint will get the job done.
Jim McGee
94 C22 Island Time
95 C30 Goin' Coastal
Maple Shade, NJ
 
#16 ·
I confess! bought one of the K jigs today! first try gave me a perfectly drilled pocket and i joined to pieces of Marine ply in a corner joint. I was impressed! :D
 
#17 ·
As with any question the answer is 'It Depends'. It depends on what your use is. I do alot of woodworking, cabinets and furniture, so if you are making something like that then yes pocket screws work very well. I would also use a polyurethane glue like Gorilla glue also unless you plan on taking it apart. Another option if you are joining corners is to use dowels and glue, or countersink screws. I would only use screws if you are using SOLID wood. If you use screws in plywood it will delaminate, maybe not at first but over time it will split between the plys.
 
#20 ·
I have used the Kreg jig on several small projects and have been very pleased. Used in conjunction with epoxy sealed/glued wood and then filling the hole with a thickened epoxy I have what appears to be a bullet proof joint. 2 years latter there are no signs of problems. David:)
 
#21 ·
I think the strength of the kreg joint in ply is because the screw angles across the plys not like straight in the edge screws. "hi lo" screws? those the ones that have a double looking type of thread?

thanks all!
 
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