Almost-A-SCAMP Progress Report #10 . . . . .

[Charles Brennan]

SKEGS:

The SCAMP has two skegs that allow it to sit on a beach, which is highly useful for beach camping.
(And for guys that don't pay enough attention to their charts, or tide-tables!) 
I'm going to put a S-S rub rail on it and don't want to risk rot in the wood, so I needed to over-drill some holes with a Forstner bit and then fill them back in with thickened epoxy.
My goal is for every fastener in this boat (as much as possible) to be sitting in epoxy and not in wood; and merely only wood-adjacent.
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Closer view of filled-in holes.
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I chamfered the holes with a counter-sink bit before filling.
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Besides gluing with epoxy, the skegs also have screws going through the hull, as this is one of the higher-stress loads the boat has to deal with.
Consensus in the various SCAMP forums, is at least 7 screws along the 7-foot length.
I used 12 screws for each skeg, but I had some other issues I was dealing with, which required additional screws.
The screws will be dipped in epoxy glue before screwing into the skegs.
However, I wanted to exclude the ballast tank from being penetrated with screws, so I measured carefully and made myself a no-drill zone.
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After a coat of epoxy . . . . .
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 . . . .  and a second coat of epoxy.
Ready for mounting!
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Check the curve/warp on the skeg to the right. 

Did not have enough room to screw in the holes from underneath, with my saw-horses in place, so I needed to use jack stands on the 4 corners of the hull, so I could remove them.
Break out the hydraulic jacks and have at it? 
Uhhh . . . .  no.
I simply lifted one corner at a time and slid the jack stand underneath, with my foot. 
Ya gotta love building a small boat. 
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I wanted a trial run for skeg placement and epoxy glue clamping pressure.
A lot of SCAMP video blogs show the skegs being weighted down with boxes of tiles, bricks, paint cans, car batteries, etc.
It occurred to me that tensile loads are every bit as good as compressive loads.
Even better, you can control glue squeeze-out, literally a ratchet-strap tooth at a time, for very fine adjustment. 
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Looks like it'll work quite well; made a few more modifications to make it quick and easy to deploy the straps, since I'm always fighting pot life of the epoxy.
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Readers of this series might remember that I had a severe warping issue with one of the skegs.   
One skeg responded to straightening, by bending it against a scrap block and clamping it over several days, but the other skeg remained far too stubborn.
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You can see the front end of the skeg wandering off to port, (remember, the hull is upside down!)  in this pic.
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My solution to this was to clamp the skeg between two 4' levels to force it straight, and then rely on the epoxy glue and the through-hull screws to to hold it in place.
(Why I needed a dozen screws, instead of 7 screws.)
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Look, Ma! No curves and warps and twists! 
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After gluing and screwing and cleaning up all the ooze-out, I FINALLY got the straight skegs I was looking for and (even better!) parallel,  + or - 2mm from each other, along their entire length.
After dealing with aerospace-type tolerances from working in the electronics industry for so many years, I thought this was amazing for a wood project.
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Thought they came out pretty good . . . . . .
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Except for one Screw-up. 
Or perhaps I should say: Screw-out.   
Hey! I was working underneath the hull in a tight space, and too close to a bulkhead, when the screw-in angle got away from me!! 
To add insult to injury, when I attempted to remove the errant screw, the screw head angle was such that I could not back it back out again and tore up the Philips head, on the screw.
Like we used to say back when I worked in construction:
"No extra charge, for tamper-proofing the fasteners!"   
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My solution was to use a cut-off wheel from a Dremel tool, to make a horizontal cut in the wood and then cut the screw in half.
That was followed by a vertical cut, so I could use a cold chisel and a hammer to break off the screw and knock it out of the skeg.
When I apply the epoxy fillets around the skegs I'll fill that in, using my wood skewer and epoxy trick.
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Ah, well.
If this is the worst mistake I make in the construction of this boat, I'll count myself as Lucky.
After the glue cures and hardens a little more, I'll add epoxy fillets around the skegs to strengthen them, and apply the final coat of graphite-infused epoxy on the hull bottom.
Then comes primer and 3 coats of paint, then the same for the sides of the hull.
Then flipping the hull over again, to finish the insides of the boat, now that the through-hull screws have been fastened.

I find myself now, always looking ahead to the succeeding building steps and planning ahead, to most efficiently devise the procedures to accomplish this.
Oh, that I had done that with my Life!   

Charles Brennan

[Norm L.]

I am truly impressed with the tension system you set up. More even and controllable than any box of bricks.

[Riley Smith]

Ain't it the truth! He's got it going on! CB, if you can find it, square drive screws are worth their weight in gold.  Maybe not a good choice EVERYWHERE, as you may have to take it loose out in the Boonies and who carries a square drive right? I'm enjoying the shop stereo and tinkering with the rig on the catboat out in the sunshine myself today. Jude was playing in the boat and found the 1894 flag up under the bow storage, so I ran it up the mast and  he thought that was cool.

[pgandw]

...CB, if you can find it, square drive screws are worth their weight in gold.  Maybe not a good choice EVERYWHERE, as you may have to take it loose out in the Boonies and who carries a square drive right?...

Even better than square drive (Robertson) are Torx head screws.  And Torx head screws are actually being carried in stainless steel in the big box stores.  I have never not been able to remove a Torx head screw.  Robertsons are ALMOST always removable.  Phillips head will strip out or break 50% of the time after being left in place a few years.

just my experiences with decks and docks and boats
Fred W

[Norm L.]

I'm with you Fred. After 2 years of furniture repair I've had to deal with a lot of nasty slot and Phillips. I did like Robertson, sometimes because it could stay on the tip of the screwdriver and good for one handed use.
 
Slots are good for household use as many things can be used to turn a slotted screw. I have a coin shaped gizmo on a key chain that fits many slot sizes. Others work better if you are using a powered drill motor and are doing multiple screws.

[Riley Smith]

I can't see the dang things anymore unless there is direct light so mostly I go by feel. The square drives bits stick pretty good and you don't need both hands like you say. I'm currently in negotiations to create a triangular drive to mess up the whole WORLD 

Ok, and about these epoxy filled holes? People have been putting various and sundry fasteners in wood for at least a couple of centuries. That was centuries where they didn't HAVE epoxy. One thing learned is that carbon steel is going to be  the death of wood in salt water. Eventually. It may take years but the thing is GOING to rust inside that wood and begin the rotting process as it expands and physically and chemically begins to alter the surrounding wood that had it encased. Not to mention the problem you may have with electrolysis in long term applications. Why the epoxy?

[Charles Brennan]

Riley, I read your post several times and maybe I misunderstood it, but I think you may have conflated two different things.

Your statement:
"One thing learned is that carbon steel is going to be  the death of wood in salt water."
Agreed.

And:
"Not to mention the problem you may have with electrolysis in long term applications. Why the epoxy?"
Dealing with two issues, here.

Screws through the hull and capped with epoxy, are embedded like a bug in amber and don't get air (oxygen) and don't get water.  Ergo, they can't oxidize (corrode) and they can't chemically react with water.

The epoxy plugs on the skegs fully accept the reality of corrosion and ultimate failure, since the screw head is exposed to the elements.
BUT! 
None of the wood is affected, because moisture can't get from the epoxy plug to the surrounding wood fibers.  As the rub rail screws inevitably corrode and fail they can be unscrewed (or drilled out and re-seated with new screws) inside the epoxy plug, without ever touching the underlying wood.

Will that work forever?
Certainly not.
But it WILL work longer than I'll be around, to observe the inevitable entropy!   

Hope this clarifies,
Charles Brennan

[Timm R Oday25]

What purpose do the grooves in the skegs serve ?

[Charles Brennan]

Timm, The grooves in the skegs serve to remind us that we are all fallible humans:

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You might call them "grooves" but to SCAMP sailors, they are called: "hand holds".
The skegs are too slippery to get a good grip on them, otherwise.

Just like a fire extinguisher bracket; one of those things you install, hoping never to use  . . . . .

Hope this clarifies,
Charles Brennan

[Riley Smith]

CB the electrolysis comment was an addendum on top of all the OTHER problems faced by metal bathed in water. Salt water even more. I threw that in there because many never even consider that aspect. The only downside that I can think of to your approach to isolating the fasteners in ythe middle of a bathtub of epoxy would be the....errr....forgot the technical term but the brittleness of the epoxy and the possibility of it "shattering" or wearing too. In a perfect world there would be absolutely no movement and no worry but that's the only thing I can think of that might be cautionary in that process. It's fun building a boat and making those decisions! And yes, experimenting on different materials, products, and processes used to get a sheet in the wind. I like the jig you set up.

 I've been adjusting and tinkering with the rig on the catboat. Doing maintenance on halyards and bridles. Which involved pulling the floatation out of the aft end and reconfiguring deck hardware. Oh fun. Yeah, it always seems the "quick little " job turns into something overblown. I didn't complain too much, being forced to work in the sunshine and listen to The Rocket 96.1. It WAS an exercise in stair stepping, getting up and down out of the boat. I guess I probably needed it. I've got it back together and NOW have to deal with those *#&($($ running lights. Maybe I should engineer a set of goal posts like you have. The previous trailer made that a challenge and I haven't actually checked this "new" one out to see. Project for today...get lights.

PS...new t-shirt slogan for post hurricane survivors. "Got lights?"

[Charles Brennan]

Riley, To avoid shattering and chipping when installing sheet metal (or wood) screws into epoxy, the two choices are:
1) Drill a suitably sized pilot hole.
The displacement modulus for epoxy is not nearly so elastic as it is for wood (although more so, than for sheet metal) so the hole size needs to be adjusted accordingly.  This however, DOES require that care be taken not to "strip" the fasteners in the hole.
2) Pre-heat the fastener (screw) with a soldering iron or propane torch before installing it. 
This is the reverse of trying to remove a screw embedded in epoxy, without breaking off the head of the screw.
Makes it pliable enough to avoid chipping or shattering.

BIG Fan of goal posts.
Here's a link to a previous post, in case you wanted a goal post how-to-do-it refresher.
https://trailersailor.com/forum/index.php?topic=752.msg4632#msg4632

Further down in the thread is a post about wiring a goal post, efficiently.

Hope this helps,
Charles Brennan

[Riley Smith]

Thanks for the refresher, after looking, this trailer is much better than the last. ( that one was actually undersized and too light) I'm completely done with working on lights as it happens every time I want to go. I want once and done.