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Spindrift 12 build log


Walt S.

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In an effort to make this thread into a seed for a Wiki page for the smaller B and B boats, I emailed Alan and Dave to ask them how they put in keel strips.  I have one boatbuildigng book by Devlin and the other by the Gougeons and neither explain how to install keel strips.  He does not think this is an area to skimp after spending so many long hours building the boat.    Devlin just recommends using 316 grade stainless steel for all rubstribs and keel strips or brass for the keel and installing the hardware with 3M 5200 or Sikaflex.  On another thread, Dave thinks that ALL hardware is a temporary installation and to use an adhesive that allows you to get it off later.  I will post Dave's adhesive recommendations in another comment.  On the process of keel strips, Alan writes

 

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I did a quick look. Online metals.com has 316 grade stainless steel bar stock. 1/8" x 1/2" x 8 feet for $10.52 plus probably $20-30 for shipping. We did this kind of thing on our Core Sound 20. Used flat bar stock on the keel instead of hollow back. We drilled and countersunk it and then screwed it down. This would be about the right size for an S-12 to protect the back end. The didn't seem to carry thinner than 1/8" which is pretty stout. 
 
What I like to do is drill my pilot hole for hardware, then install the hardware, once i'm happy with everything, I take it all off and use a pipe cleaner dipped in regular (not thickened) epoxy and stick it down in the hole to soak some epoxy into the wood grain inside the hole. Let that cure then re-install the hardware with either butyl rubber blobs on the screws and underside of the hardware contact face or using some other "boat caulk". 

 

Alan also recommends bedding Anderson/Elvestrom bailers in with liquid butyl rubber after routing out the bailer inset and putting a few coats of epoxy on it.  Graham likes to put his bailers in directly with thickened epoxy. 

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Here's Dave's guide to hardware adhesives:
 

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Jamestown Distributors used to publish a chart with the tensile strengths of bedding/sealants.  I found it very useful and memorized the key products I used  They went in order of bonding strength:

1. 3M 5200 - 700 psi  polyurethane - extremely adhesive ( I use this only when I see no need to take it apart ever.  There is a serious danger of damage doing so.)

2. 3M 4200 - 300 psi  polyurethane

3. Sikaflex 291 - 220 psi  polyurethane  (I use this when I really want white that won't yellow and I can live with the nuisance taking things apart later)

4. 3M 101 and BoatLife LifeCaulk - 150 psi  polysulfides  (These are my beddings of choice for hardware.  The only problem is that the white will yellow over time.)

5. Dolfinite - nil -  oil based goo - not an adhesive at all  (AKA  boatyard bedding.  This is the product from the old days.)

 

OK, they still have one, but I had to look:

https://www.jamestowndistributors.com/userportal/document.do?docId=1170&title=Marine+Adhesives+Strength+and+Usage+Comparison+Chart

 

I find the most important technique for using any but Dolfinite is to smear both surfaces and make sure no bubbles or voids exist, then put them together with at least some ooze out all the way around.  Masking can make clean up easier and in some cases I leave the ooze  to cut off later with a utility knife.

Here's a good write-up on butyl tape:

http://sundownersailsagain.com/butyl-tape/

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Walt asked me to comment on bending and bedding SS keel strips.  He is considering flat and hollow half oval.

 

I do the bending first.  I make a template of the stem and trace it onto a piece of scrap plywood.  I screw small blocks of nominal 2X along the line spaced out a few inches and beyond the curve a little in both directions.  This helps keep the curve fair.  I then clamp one end of my stock to the block representing too far up the stem and slowly bend and clamp the material around the blocks.  DO NOT drill screw holes first.  These may cause kinks or pinches in the material when you want a smooth fair curve.  Half oval can be tricky to bend.  A slow even bending of the material is important to avoid kinks   A rubber mallet can be helpful.

 

When I am happy with my dry fit of the curve I cut off the few inches that I first clamped to where I want it to actually end and drill the holes.  I put a couple screws close together at the bow and space them out more along the curve to the straight portions where I use 6" centers usually.  I then fasten this forward piece in place and either mark off where to cut the aft end, or fit the second section needed to go the whole length.  When the entire chafe strip is installed and I am pleased with it I am ready to remove it for the actual bedded installation.

 

I usually bed keel strips in polysulfide (LifeCaulk or 101).  Sikaflex is also a good choice if you want a bit more adhesion.  But when mechanical fastening is the method it isn't really needed. Anything more adhesive will make replacement/repair harder and this is considered a sacrificial piece.   The nice thing about hallow half oval is that is captrures goo in the space it creates between the hallow and the keel.  If you apply the goo well, this will become a great gasket for all of your fastener penetrations as they (screws) pass through this gasket before they penetrate the keel.  With flat stock, or solid half round/oval you have to be a little more careful tightening the screws so as not to starve the joint of goo.  I ALWAYS apply goo to both surfaces being bedded together.  This helps assure there are no voids.  I put a thin smear on one surface and enough on the other to assure there is too much in total and I will get some squeeze out during fastening.  This is the only way I know to assure you end up with enough and no voids. With flat back material it is key to tighten the fasteners to snug without squishing out all the goo.  Some suggest tightening the screws again after the goo cures.  I think this is a huge mistake.  The goo has bonded to the screws as well, and tightening after breaks that bond and you lose the integrity of the seal.  It is the wood penetration by the screws that you are most concerned about.  I have never bothered to epoxy the screw holes between dry fit and bedding, but this does not hurt any.

 

Sort of a side bar, regarding butyl tape.  I have only used it for glazing, but it surely has been a successful method on boats too.  Because it is rubber that has never been vulcanized it stays soft for almost ever.  And because is it firmer material it might be easier to snug fasteners without starving the joint.

 

Hope this is helpful and best to you on the finishing.

 

 

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I agree with Dave's comments. Additionally, use small, short screws to attach the half oval. I use 1/2" long, flat or oval headed #8's most commonly. The idea is to attach the strip lightly, so if you do bash into something hard, you'll tear or break these light fasteners and maybe lose the section of strip, but not rip holes in your skeg or tear the whole skeg off with the impact. With sailboats this isn't as common as with powerboats, which can easily rip off a rub strip, but the logic is still valid.

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4 hours ago, greendane said:

Bedding of the strips is over paint, yes? 

Absolutely.  If you bed hardware first you get a mechanical seem where the paint meets the bedding.  The overlap of painting/varnishing first and bedding over it is very important for all hardware.

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Dave means, "3M 101 marine sealant," when he writes, "101."  This is probably what I'm going to use for all hardware except the Beckson deckplates which say they require pure silicone for bedding.  

 

As to the butyl rubber, this seems like a good option if you can identify a good brand.  There is a wide range of quality, workability and cure times for liquid butyl rubber and tape based on the reviews I've read.  There are not strong incentives to make high quality products in the construction industry these days.  

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2 hours ago, Walt S. said:

Dave means, "3M 101 marine sealant," when he writes, "101."  This is probably what I'm going to use for all hardware except the Beckson deckplates which say they require pure silicone for bedding.  

 

 

Yes, polysulfides should not be used with plastics.

 

Manufacturers of acrylic and polycarbonate also specify silicone for glazing.  The issue with silicone is that once it touches a surface it can be near impossible to ever get anything else to adhere.  Mask very well anything you bed in silicone.  You may have to paint or varnish there again some day.

 

edit: The only real down side to non-skid surfaces is keeping them clean.  I won't use them if I can find another way that is reasonable.  I went so far as to make Teak floor boards for my Lapwing.

Edited by Hirilonde
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Note that Graham uses thickened epoxy for gluing his plastic beckson type screw ports onto his boats in addition to using it to install anderson bailers. I didn't like the idea when I first heard him say he just glues them in but the more I think about it, the easier it is. How many times have I ever had to remove one? maybe once. And if you're removing it, it's likely damaged and can be cut and taken out as a "split ring". 

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14 hours ago, Hirilonde said:

The issue with silicone is that once it touches a surface it can be near impossible to ever get anything else to adhere

If you get within 100 yards of a car factory (where they are painting car bodies) with a tube of silicone you'll be sleeping with the fishes...

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18 hours ago, Alan Stewart said:

Note that Graham uses thickened epoxy for gluing his plastic beckson type screw ports onto his boats in addition to using it to install anderson bailers. I didn't like the idea when I first heard him say he just glues them in but the more I think about it, the easier it is. How many times have I ever had to remove one? maybe once. And if you're removing it, it's likely damaged and can be cut and taken out as a "split ring". 

 

If you use epoxy, why even through-bolt the deckplates and bailer in?  In some of the pictures on the B and B website, it looks like the deckplates are just glued on without hardware.  

 

I was thinking about how I didn't want to have to wait for 3 coats of epoxy to cure before I bedded-in the bailer.  It's great to know I can just glue it right in. 

 

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On 4/14/2017 at 4:05 PM, Hirilonde said:

 

edit: The only real down side to non-skid surfaces is keeping them clean.  I won't use them if I can find another way that is reasonable.  I went so far as to make Teak floor boards for my Lapwing.

 

Thanks.  The more I think about it, the less appealing non-skid sounds.  In bare feet, it won't be pleasant.  It doesn't grip well when wet.  What do you think of this stuff instead?

 

https://www.fisheriessupply.com/safety/non-slip-products

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I never found non-skid uncomfortable in bare feet, though some of the large aggregate stuff like walnut shells I bet are.  Some of them grip well when wet, Interdeck is one.  They just seem to hold dirt streaks and scuff marks tenaciously.

 

I can't speak to any of those products you linked first hand, but today's technology is pretty good.  I would also consider some kind of foot block you could use that would be removable if your major concern is rowing.  You don't really stand and walk around a lot in a Spindrift.  You can always scuff up the sole of your boat and add non-skid paint later if it proves necessary.  I painted the sole of my 9N and have concluded it wasn't really necessary.  But then I haven't experienced not having it.

 

If you do end up with non-skid, be it paint or mats, I find it looks best if you mask off the sole inboard of the sides, transom and bulkheads such that the corners are not non-skid paint, or cut the mats to such a pattern.  Note the patterns PAR made for the deck in one of his photos in another thread.  It just looks really great when you do such things.  It looks like you framed it in.

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Dave is right. You definitely need non skid in the cockpit. When it is wet, which is often it will be lethal. One slip and you will pay for it. You do not need aggressive non skid.

 

The paint stores sell non skid powder which is micro spheres. Some have three grades, the medium is about right and is comfortable and will give a positive grip and is comfortable with bare feet and to kneel on.

 

Once I tried rubber grindings from a tire re-treader. After it was sieved and sprinkled into the paint and painted over I had excellent non skid. Like most "great ideas" there was one issue. They only make tires out of black rubber and after a while I had black spots showing through the paint.

 

The year before last while at the WoodenBoat Show at Mystic there was a vendor selling granulated white rubber for non skid. When I showed excitement and told him of my many non skid adventures he asked me for my card.. I do not know if he felt sorry for me or he hoped I would recommend it but he sent me enough for Carlita. I really love it, I think that it is the best yet. It looks good, is comfortable and very positive and is holding up so far and no black spots.

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