Miscelleneous HWS Questions

For all the HWS gurus…

sorry but you know me…

questions, question, questions

and always out of the box stuff…

anyway,

My brother(Sharkbait) and I have been seriously bitten by the HWS bug and have our own competing projects going on.

My brother’s being Mr. Soul and a fanboy of PaulJ is building his skeleton out of 1/4" balsa using 1/8" balsa for the skins and rails. He took all my clamps as well to his under house shaping room…

Me, on the other hand being the ever eclectic mad scientist took all my left over 4’x8’x2" blue dow and cut out my frames from it parallelling solomon’s strategy. I then cut all my 2" thick blue dow frame components into 1" thick frames on our el-cheapo band saw and now have enough for two boards. My plan is to bag glass my left over 1mm bamboo weave on each side of these 1" thick blue dow foam frames to create something similar to those foam core component walls they build houses and other stuff out of on the mainland. I’ll then bore out all the holes and glue up the ribs to the spine using short 1/4" square hardwood vertical braces glued into the cores of all four intersects where the spine and ribs meet.

I kind of like the idea of a totally water proof internal structure as well as using the strength of the vertically oriented 1mm woven bamboo reinforced by the waterproof and lightweight blue dow core in between the two sheets of 1mm bamboo.

My questions surrounds skinning options and what’s the minimum I should be doing for skins.

As I said my brother’s looking at using 1/8" thick panels of balsa strips, my understanding is that for HWS you should be looking for a minimum of 1/4" thick deck and bottom skins over your frames.

so…

Q1. what is a good minimum thickness for a skin? 1/8" or 1/4"?

Q2. As far as options I found a bunch of 1/4" poplar in 2"x48" through 6"x48" widths and lengths.

would a glued up panel of this 1/4" thick poplar just be too heavy or stiff for an HWS deck or bottom?

I was also planing in mixing the 1/4" thick poplar with 1/4" balsa strips with the 6" wide poplar sitting over the stringer on the bottom and over the ribs on the deck.

If 1/4" is too thick , I plan on kerf or band saw cutting the 1/4"x2"x48" poplar strips in half to get it between 1/8" and 1/16" thick.

Q3. Should I try and kerf the 2" wide strips in a table or slice it on a band saw? both ideas seem spooky from a handling perspective to me.

Q4. I was able to get enough 5/16"x4"x8’ bead and cove knotty pine panels to make a 43"x96" panel of knotty pine for a bottom or deck skin panel. I like the look but will it work as a HWS skin? Or is it just too soft of a wood? I plan on glassing both sides and like the idea of sanding the pine panels once I get them over the frame.

Q5. Another one of my crazy ideas was that once I built the internal frame and attached the first layers of 1/8" balsa along the rail for support. I was planning on routing out a 1/16" groove in the deck and bottom 1/4" thick panels to set the spine and ribs into the deck and bottom skins and then PU or 3M 5200 glue both skins at the same time in a vacuum bag. Dumb idea? Never seen anyone do this yet.

Q6. Finally I’m also thinking of pre building out deck and bottom skins by vacuuming forming them over a mold board using 1" thick 1lb EPS covered on the outside with the 1mm bamboo and do this groove thing on the inside of the 1" EPS before glassing the frame onto the preformed panels. Kind of like reverse engineering a hollow from a sample mold using vaccum tech like they do in other industries using either cheaply reinforced(using bamboo versus carbon) cheap 1" thick EPS foam panels or more expensive 1/2" thick corecel. Having seem anyone take this approach either… Maybe there’s just not enough “soul” in it or maybe it just doesn’t work. And yes, I did read Paul’s blue foam experiment and didn’t get it as it seemed over built with all the carbon put on it.

Sorry for all this silliness…

Pics of all the pieces and effort will be forth coming as the project continues…

Hi Oneula,

I have had one board which had a 1/4 inch balsa deck glassed with 6 ounce, it survived 3 years of constant abuse , but at the end of that time it had patches all over the deck from where I had cracked the balsa. . . it wasn’t a domed deck, which makes it weaker, and it had frames spaced every 2 inches. . . also it had no cloth under the deck. . . . the 1/4 inch bottom was fine. . … . .convex and no one standing on it. Also i have damaged redwood decks at 1/8th of an inch thick (glassed)and 1/4 inch thick but unglassed. . . . . the latter damaged in one spot after several years of use, the former cracked regularly and repaired on the run with pieces of woollen blanket soaked in west system.

Regards

Roy

Q1. what is a good minimum thickness for a skin? 1/8" or 1/4"?

1/8" balsa doesn’t leave much room for fine tuning the bottom/rail junction…1/4" is a bit stiffer in areas that it needs to be…Besides, what’s the real weight savings…The weight adds up on the rails…

Q2. As far as options I found a bunch of 1/4" poplar in 2"x48" through 6"x48" widths and lengths.

would a glued up panel of this 1/4" thick poplar just be too heavy or stiff for an HWS deck or bottom?

Poplar is kinda heavy, but not really…I’d plane the poplar to 1/8" given the density/hardness/stiffness of the wood…It should feather in more easily at the rails than balsa without the sand through worry…

I was also planing in mixing the 1/4" thick poplar with 1/4" balsa strips with the 6" wide poplar sitting over the stringer on the bottom and over the ribs on the deck.

Tough to sand and keep even…Ridges and troughs…6" wide should be fine on the deck, but on the bottom if you have any kind of significant vee or bottom roll you might have a hard time getting it to sit right on the frame…

If 1/4" is too thick , I plan on kerf or band saw cutting the 1/4"x2"x48" poplar strips in half to get it between 1/8" and 1/16" thick.

Good luck…I’d use a surfacing planer…

Q3. Should I try and kerf the 2" wide strips in a table or slice it on a band saw? both ideas seem spooky from a handling perspective to me.

It depends on how comfortable you are with the specific tool… I’m a tablesaw guy…

Q4. I was able to get enough 5/16"x4"x8’ bead and cove knotty pine panels to make a 43"x96" panel of knotty pine for a bottom or deck skin panel. I like the look but will it work as a HWS skin? Or is it just too soft of a wood? I plan on glassing both sides and like the idea of sanding the pine panels once I get them over the frame.

It should be fine…Not too soft…

Q5. Another one of my crazy ideas was that once I built the internal frame and attached the first layers of 1/8" balsa along the rail for support. I was planning on routing out a 1/16" groove in the deck and bottom 1/4" thick panels to set the spine and ribs into the deck and bottom skins and then PU or 3M 5200 glue both skins at the same time in a vacuum bag. Dumb idea? Never seen anyone do this yet.

I have no vac bag advice…

Q6. Finally I’m also thinking of pre building out deck and bottom skins by vacuuming forming them over a mold board using 1" thick 1lb EPS covered on the outside with the 1mm bamboo and do this groove thing on the inside of the 1" EPS before glassing the frame onto the preformed panels. Kind of like reverse engineering a hollow from a sample mold using vaccum tech like they do in other industries using either cheaply reinforced(using bamboo versus carbon) cheap 1" thick EPS foam panels or more expensive 1/2" thick corecel. Having seem anyone take this approach either… Maybe there’s just not enough “soul” in it or maybe it just doesn’t work. And yes, I did read Paul’s blue foam experiment and didn’t get it as it seemed over built with all the carbon put on it.

Do it…Yeah, that blue foam board is overbuilt…Surfs good though…

It’s all just one big crazy experiment…

Sorry for all this silliness…

Pics of all the pieces and effort will be forth coming as the project continues…

Oneula:

Unless you have used the 5200 before and are familiar with it, I’d tend to recommend other alternatives. In the wooden boat literature, it’s usually described as “bedding compound”. It never completely hardens (that is actually its advantage) and is very messy stuff. Doc can no doubt enlighten you further. Here is a typical description from a site on yacht maintenance (http://www.yachtsurvey.com/dealing_with_leaks.htm):

“5200 is like working with tar. It has a way of getting all over everything, no matter how hard you try to be careful. That’s one of the reasons it’s so good; it sticks to anything and everything. When working with the stuff, you should have plenty of rags and a quart of acetone handy. Once you’ve used a rag to wipe up excess, get rid of that rag as that rag will transfer 5200 to everything it comes in contact with, including you. It’s a real tarbaby. Clean your hands the moment you get some on them, otherwise your fingers will transfer it to whatever you touch. You won’t notice this at first, but weeks later dirty finger prints will start showing up all over, and they do not wipe off. Once it’s cured, 5200 is no longer soluable with anything.”

-Samiam

I agree with iam2sam 5200 should not be used as a glue where there is no mechanical fastening. It just takes to long to set up. Great stuff in the right place{ thru hull fittings,depth sounder blocks ect.) But to use it to glue something up is a problem, unless you can leave it clamped fore a week. (or more). I use a lot of epoxy at work and you cant beat it for gluing wood. I am building my 2nd hollow board now and am going for a lot lighter construction. 1/2" foam(green divinalcell) for the frame and 1/8" ply for the deck and bottom Cherry this time. I am thinking about a 1/8" stringer on each rail of spruce. and foam rails. Not really a hwb more like a hybrid?? Any way like PJensen says its all one big experiment. This board is 6’6" 21"1/2 25/8" with 3 fins so I just dont want it to be heavy at all. That bamboo stuff sounds pretty cool. I was going to use a flooring material I had left over that was laminated bamboo. I resawed it and planed it down to a little less than 1/8" Really cool stuff but I just didn’t have enough to do everything. Would love to get more info on what your bamboo stuff is.

…you should have plenty of rags and a quart of acetone handy.

Oneula,

Please dont follow this advice…plain old alcohol works excellent.

5200 is an excellent adhesive and has its place. As does GG. And yes it can be messy, but thats why man invented GLOVES. What can we say about the ‘operator’ when he uses chemicals w/o proper protection?

As usual, use the right tool for the job.

Hi Onuela,

Me giving you advice?

Well, I just want to second one thing that Paul J said regarding mixing poplar and ply. I had alot of trouble with the high density foam inserts on my Plywood/EPS. The different densities sand different and no matter what I did it seemed like there was (to my eye) a bump. If you look in my posts you will see it. It’s right where the forward fins go, so now I’m looking at it as a design feature- a bump swallow. And in my adveritising (yeah right) I will say how it creates a pivot point for smooth tight radius turning.

Balsa and cork on the other hand sand together nice. The cork makes a nice noise that lets you know you’re cutting. That must be why Paul uses them together. Thanks Paul.