Torture boards

Having seen more than a few flat spots in my boats hull after relaminating, can someone give me some specs regarding making some sanding boards to correct this.

Lengths, widths, thickness of ply etc and what worked best.

cheers

roger

www.agentlemansyacht.com

 

I use 1/4" and 3/8" and buy sandpaper by the roll because is cheaper, but they come in 2 3/4" X 16 1/2" too. If you are doing large flat panels thicker plywood would work OK.

 

I just made one from a scrape 1/2" CDX and some cedar planks cut offs for handles. The 1/2" is a bit rigid so Gonzo is spot on for his thicknesses. I buggered up a 3" x 21" sanding bent that was far from used up and made the board about 19" so I could wrap the sanding belt around the ends and staple it away from the sanding surface. I'm thinking the sanding belt will last a good long time before wearing out.

 

I've used just about everything for long boards, aluminum, steel, acrylic and polycarbonate sheet and of course thin plywood. 1/8" and 1/4" are the usual choices, with 3/8 and 1/2" generally being too rigid.

You can also do a good job with a home make disk sander, to knock down the highs I use a full sheet of paper on a 1/4" plywood square, that's had it's corners well rounded so it doesn't dig in. It takes some getting use to, but is effective in the early stages of fairing.

It's all about technique, more so than the tool.

 

Thanks for the replies guys, theres plenty for me to work with from your suggestions.

cheers roger

 

Think X pattern- 45 up and to the right then 45 down and to the right. Change the paper often and early, its cheaper then your time. By the time you get match fit and toned you'll be finished!

 

One quick solution is to use one of the Polyurethane 'Floats' used by plasterers and renderers. All good toolshops and builders merchants have them. Down side is they are quite short so only good for limited length fairing. These are perfect width for sand paper off a roll and the handle is good too. Just double side the paper on with wide 'carpet' type tape.

If you are making one, for longer fairing, perhaps bizarrely, the handle size and length is critical to making it comfortable to use. If I remember right from when I last made a fairing board around 90-100mm (3 3/4" to 4") is about the right length for the finger opening. Then your fingers keep control of the board without slipping. Larger apertures are not good news and will give you problems. Only if you have very large hands will you require a longer opening.

 

Rather than handles, I prefer grips. These can be knobs or rails, usually undercut a bit and rounded for a good grip. I find it more comfortable to grasp and shove then to grab a closed loop style of handle. A grip also can place you hands closer to the sanding plane, which makes it easier to work the board, in my experience.

 

Interestingly i filled and faired the hull using only dry lining tools, (hawk, trowel and various width taping knives) they lend themselves perfectly to working in confined spaces as well as all the different curves both convex and concave.

With regards the sanding boards i'm probably gonna go with door knobs as rails will make the board too stiff as i need to get the waterline sorted which is the problem area especially midships going aft where tumblehome is greatest therefore curves in this region are quite tight in radius .

What do you guys think of adjustable rubber sanders?, i see Eastwoods offer them in multiple sizes and sold in kits with the self adhesive paper. The only problem i could see with these sanders is i've only found one place in the uk that sells the PSA paper (Frost's) and they only offer it in 80, 120 and 220 grit. But i like them because of the rod system whereby you can adjust their flexibility.

Any thoughts

 

Also do not ignore the bodyshop 'aluminium' files which in a holder can be curved Convex or Concave. Unfortunately the 10" ones are no longer available. But 12" and up are. Very good on glass, whether epoxy or polyester as the blades last a long time. Probably one of the most 'used' tools in my armoury when dealing with glass repairs and gelcoat.....

Interesting PAR, agree, the 'plane' type handles would work fine. Don't think I've faired anything beyond 32' and that was with a two hole board that worked fine. Mind you being a custom board and keeping the hole/finger cut outs low it worked OK. Agree totally about the control - low down to 'feel' the surface and not roll over and be remote. So I'd guess your door knobs need to be similar to plane front knob shapes, not all are.

On sanding blocks, well my preference is to use my own wooden ones made from jellutong. A bit firmer than cork but not super hard either. Ironically probably closer to the rubber ones, but I just don't like them much. Find what works for you. I have used the cork, rubber and other commercial types but ended up preparing my own, btw they work wet or dry.

Papers, well any half decent stuff will do, the Finnish Mirka brand is good and some places will sell X meters from a roll. Depending on how rough you are finishing from, I suspect 40, 60 and 80 will be your best friends. You can use an orbital 1/2 sheet sander to do quite a bit as long as you know how to 'work the diagonals' and finish by hand with the board.

 

I screw two pieces of broom sticks. They allow me to rotate my hands for a better position as the angle changes.

 

Suki where abouts in hampshire are you?, i'm in the same county (Ringwood) if close enough wouldnt mind getting you to take a look, no worries if you're not.

cheers

 

What he said. The standard length is approx. 1.8m or something. Cut it to about 80cm. Buy sturdy clips like you get on clip boards and screw them on. Then you don't have any problem with holding paper. They are the width of the standard paper on a roll. They have handle along the length.

Board with p40. Remove these scratches with machine finer paper. Depending on the primer you use p80 machine is good enough.

Happy sanding It is good for you I am still fit and slim after 1000's m2 superyachts. Obviously the better you fill the less you have to sand. You should only be taking off the small imperfections. It is often better just to fill 1 more time. Note that some of the superyacht yards eg Feadship never board....but they fill loads. I came from background of in our ultimate 5 times fill then board...then board the primer as well. But then we got it better than Feadship in less time

Speak to Marineware. They are the awlgrip distributor. They maybe have boards or will know where to buy. We get ours from YEC in NL but as stated they are a builders tool in theory.

 

Thanks Roger.

Ringwood is a fair drive A31, M3, M27, A31 again, maybe 65 miles. I am nearly as far to the north east of Hampshire as you can get. Well not quite, but near the Devils Punchbowl and the Surrey border. I estimate about a one and a half hour drive down to Ringwood. If I am down that way, I'll get in touch. V busy on a load of stuff right now though, a lot of finish sanding and buffing.

 

Cheers suki, yeah definately drop in if passing by.

Roger