Are there new ways to fair hulls

Having been in the shipbuilding industry for many years now
it seems that the fairing[boging] of large hulls is still done in the
same way regardless of the type of material used ie on alloy or steel hull constutions.
Has any one come across new methods of fairing, new machinery
or ways that it is done?
If you have seen any thing out there it would be great to hear your comments or idears thanks
shane

 

Hi we just finished fairing our F - 39 trimaran, we started out using long boards and lots of muscle, then read about the Power Board from another home builder, it was an absolute life saver. They have a professional model and a smaller version for the home builder.

 

OK, So what is a "Power Board" and where can we find some information on it?

 

Maybe Glenn Ashmore's power boards ???

"The heavy duty one is based on an old sears 3x12 belt sander. I chopped off the front and bolted a frame to one side. The frame is 1" square steel tubing with stubs welded to the side for the belt to ride on. The front roller was mounted to the far end of the frame and a 1/4" plywood platen mounted in between"

 

"The other sander is an air file with the standard board removed and a 3"x36" piece of 1/4" plywood in its place."

See: http://www.rutuonline.com/html/long_boards.html

 

Hay Baby

Hey Are You There

 

Hi Shane

Why not built your steel hull fair in the first place?
Prevention is better than cure. :idea:

Without polishing my own badge, I have built 18 steel yachts between 8 to 20 meters LOA. The most filler I used per hull was about 4 kg to level of some small hollows etc.
Much of my fairing was done with a spray-on filler and wet sanded down to a glasslike finish. Again, this is only possible if you have produced a very fair hull.
The thickest hull plating I used was 4mm - even on the 20m (65ft)

To produce a fair hull, try the following;

1. Start with a decent design by a designer that specialize in good steel designs - ignore designs with transverse frames welded to hull plating like the plague. Longitudinal framing is the way to go.

2. Through away the arc welder, use a MIG unit, weld plates on inside, back grind from the outside into the inner weld, weld up. Try to do most welding in vertical down runs. Less heat transfer and grinding afterwards. Penetration ok if machine set higher than normal. Stagger welds, weld both port and starboard sides simultaneously

3. Most importedly, grinding. If you take a 1 mm nib out of a 4 mm plate with a grinder, (very easy) you destroyed 25% of the plate!!
I usually grinded the welds down to just about a 1mm above the plating, (extreme care to be taken not to touch the plating) then loaded a paper sanding disc and rubber backing pad (80 grit) to grinder and smooth down welds to plating. Paper dics usaully only grinds of "high spots" and leave plating smooth.

It really makes my hair stand up when I see a steel built yacht plastered all over with a thick layer filler and then weeks spent sanding it down.

I once repaired a steel hull that started loosing it's "skin" of fairing compound. A very sad sight indeed.

 

Fairing Hulls

Wynand, you are bloody right! In spite of that, if you enter a commercial yard, things might look different. Good welders are as scarce as Derbywinners in a hackstable!
A few hullbuilders - I can mention 4 or 5 in Holland - do feed your bill. The rest?
Answer for yourself. Some amateur-builders are factually superprofi's, some professional builders are in fact amateurs.
If I ever can afford a new boat, I'll come to you - you speak my language, niewaar?

 

Beste groete D'ARTIOS

Dankie vir jou ondersteuning in die verband. Ja, dit is regtig maklik om 'n ordentlike boot te bou sonder al die fillers en goeters. Jy is heeltemal reg, baie tuis bouers is beter as proffesionele bouers wat regtig 'n skande vir die industrie is.
Dit sal vir my 'n grote plesier wees om vir jou 'n boot te bou. Soos ek al in jou poste agtergekom het, praat ons dieselfde boot taal. Ek sal jou graag eendag wil ontmoet as ek in Nederland kom. Ja, ek kan Hollands lees en verstaan.

Sorry about this people, just a little private conversation between Dartios and myself.

I totally agree with D'artios about some proffessional yards. Some are there just to pocket your hard earned cash.

 

One way to deal with the fairing issue: Instead of putting a lot of fairing compound on a hull and then sanding it into shape, one can use strips of plywood that have a non- adhesive surface (i.e. wet- room panels like respatex) You screw strips of this panel to the hull panel that will be faired, for example a topside of a hull plug under construction, non- slip surface facing towards the hull. You need one strip at the chine, and one strip at the deck. You attach it to the hull with a certain spacing between the screws and leave a small space 5 mm or so between the hull and the strips. Now you put fairing compound behind the strips and let it cure. Then you remove the strips and use the fairing- compound strips that are now left on the hull as a reference or guide when you put fairing compound between the strips, on the whole surface. Now you can make a good finish by following the guides. You must apply fairing compound some 3 or 4 times, and you scrape away exess f. c. using the guides. If you get the idea here, fairing will never be an issue again. It is fun, gives many possibilities, good control over the finished result and a great advantage over that stupid sanding- into- shape. The scraper that you use can have a convex or concave shape, so that you get the double curvature that might be desirable on bottom panels and top- sides, for example. You can use this technique on any surface you like. I shouldn´t be telling you this secret, I dont know many pattern- makers that use it. If they only knew..

 

Hi T:Jacobsen

I asked this it in an earlier post, Save you a lot of trouble and $$$.

I attached three photos of boats I have built.
1. Dix 65, busy shot blasting and epoxy prime coating (no filler on the hull, and fair as a baby's behind)
2. Dix 65 and Dix 57 (inverted) The 57 ready for grinding smooth welds.
3. Close-up of bow section on Dix 65 - traditionally the most difficult part of hull to get fair. Note the smooth and even plating.

Filler to my mind is the hallmark of poor workmanship Ok puttymen. stone me......but, think about it with an open mind

 

Hi, Wynand Nortje. Your boats look impressing!

My comment on fairing hulls is not really relevant for you steel- boat enthusiasts. I am more into plugs and molds for fiberglass boats. Filler on a steel hull might be the hallmark of poor workmanship, as you say. I don´t know, as I am not into that field. But putty might be to a patternmaker what clay is to a sculptor. Think about all the exciting shapes that you can make with clay or putty. Steel or wood are wonderful materials if they are in the hands of good craftsmen like you, but there are some limitations when it comes to the shapes you can create with it, yes?

I saw a nice steel sailing boat some time ago. it was 50 feet long and had a round bilge like yours. The boat builder had taken the panels to a place where they keep a lot of sand. They dug a hole in the sand and run over the panels with a big truck to shape them, I was told. I found that very interesting.

 

a question regarding hull plate thickness

Hello Wynand N, great pics and very interested to read your advice thankyou.
Could you please suggest what your optimum steel plate thicknesses would be for an 8m boat? It's hard to find information regarding very small boatbuilding in steel as it is generally considered only for larger craft.
Cheers
Phil

 

Metal forming flatsheet to curves has not really changed in 100 years for a curved shape-car fenders, only one in any type of metal, still requires hours in front of a rolling dolly Why do you think wood is still used?

 

Hi Phylus

Thank you for your kind words.

I would recommend a hull & deck unit of 3mm (1/8 inch), frameless construction with keel reinforcing (floors) and logitudinal stringers. This type of hull you build over a temporary frame former and the hull is quite lightweight.

In fact, many years ago I had built 6 x Tom Thumb 24 (7.3 meter) sailing boats to the above type of construction. My own Tom Thumb 24 was sold to a young adventurer twho took it on a circumnavigation around the horn, and is back somewhere in the pacific.
If you send me an email, I will send you photos of construction, from building frame to complete Tom Thumb 24 boat. jmwnortje@lantic.net
By the way, I am in the mood to do a design of a shoestring budget steel boat for the DIYer. Raduis chined, LOA 8m, Disp 4 tons. Interested?