Fairing steel hull

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jmp

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Trying to find out if epoxy with filler additive can in practice be plastered onto a steel hull to fair out and smooth the welded panels. I have tried the West site without success ,but feel perhaps a forumite may well have some ideas,or better still experience?
The situation is a new hull painted with epoxy after the blasting and I beleive the correct preparation and finish.The panels are too clearly visible for my likes which ruins the overall aesthetics.

Any help or suggestions would be much appreciated.
 
have you considered how it'll look when the hull flexes ?
might not be a good idea if you put lots on

cheers
Mick
 
yes

see awlgrip site for instructions

see bank manager for loan, as awlgrip product must contain 90% gold or similar
 
Currently Fairing my new steel yacht hull.

Most fairing conpounds are epoxy with micro baloons (hollow glass sphers) I got mine from a local company.

I am positive you can get it made up locally or you cound get the components from the west people and mix it yourself. It may also be cheaper
 
speaking as a steel boat builder you want to think long and hard about using filler to fair a steel hull.... its sounds as if you are trying to get rid of the "hungry horse" look that a lot of steel boats have, this is caused by incorrect welding of the hull plating to the frames, plating should only be stiched to the frames where it touches them and not to much weld should be laid down at once as this can cause major distortion,
the heat makes the plate expand and as it is now fixed in place by the welds it has only one place it can go and that to dish in between each frame.

if you feel that you really do need to fair your hull then preperation is the key but even then you are not guaranteed long term results...there are two schools of thought first and I think having seen the results I would go down this road if I really had to... apply an epoxy filler direct to the grit blasted ( blasted to sa 2.1/2 ). this appears to give the best adhesion to the steel but you have to do this very quickly as you only have about 20 mins before the blasted area will flash rust. if you are making your own filler you need to choose an addative that is flexible and easy to sand or you will be sanding your hull to get a fair finish forever.

if your hull is allready painted you have to question the intgrerty of the paint system because you will be applying filler to paint that might not be correctly adhered to the hull.
bare in mind that if the whole hull needs to be done then it is a massive undertaking... not putting the filler on but the rubbing down and over fairing that will be needed to be done!

Why not to fair .....steel is not the ridged material that people think it is ...infact its very very flexible not only that but it does have quit a high expansion and contraction rate, there will be a marked differance in the size of a 45 footer on a really hot summers day compared to a really cold day, that does'nt mean that all your filler is going to drop out next summer or winter, what it does mean is that gradually as the hull expands and shinks it will do so at a slightly different rate to the filler, and over time this will break down the bond between the filler and the steel.
If you intend to do some serious sailing you will know that there are times when you cannot help but be in a situation were the hull is dropping of a wave into the troughs when this happens I'm sure you will have felt the whole hull judder, all hulls do it regardless of what they are made of when this happens the hull is changing shape dramatically .......and ya filler is going to drop out.....
I've seen a 50 footer which had been extensivly faired with filler and all the stb fwd quarter had its filler missing !!

so do you really need to fill ? I would go for a paint scheme that will tend to hide the hollows and avoid colours that will emphisize it.

on a final note I once had to repair a hull that had a large section of corrosion, an area of about 2 square feet which had took place due to moisture and air getting in behind the filler this was not noticed untill the filler started to get large blisters in it and went the same way that can be seen on cars when they have been filled sometimes.
my own steel boat is not 100% fair and I was really carefull when I built her ...but so what !!
steel is one of the best if not the best material for a cruising boat ...just live with it..
and remember this if you do a bit of racing don't shout "starboard" just shout "steel" and everyone gets out of ya way....
hope this helps
Rachel. /forums/images/graemlins/smile.gif
 
Well alot a of assumptions there.

Having been in heavy mechanical engineering for over 40 years I think I would have some idea of welding and in general my hull does not have a "Hungry Horse" look. There is some distortion where the plates have been welded together, the fuel tank was welded in and where the stern was modified but no ribs showing (ribs no even weldes to plates only horizontal stringers.

The hull and topsides were all grit blasted using hard platium slag direct from the mines in South Africa and the place I am building is very dry so rust is very slow to form (in most cases the "experts" say 4 hours is the norm) but at 2000m above sea level 600 Km from the sea it is very dry in winter as we have NO rain then.

I wanted white gloss finish so some fairing was needed. If I just wanted a "utility" yacht I would have grit blasted and printed with epoxy tar all over. I used epoxy tar below the waterline and all epoxy above and inside to a thickness of at least 400 micron.

You can see some pics on my web site (URL in my bio) (I do not see you have filled yours in yet so do not know where you are)
 
why alot of assumptions?

the original poster is here in Nottingham England = cold+damp even in summer sometimes we don't have the best conditions for grit blasting and painting unless inside with carefully controlled conditions, and getting the humidity right in a building shed of the size we are talking about is very expensive. hence the reason nearly all grit blasting and painting is done out side here.
I can only speak as I find from experience from building both pleasure and comercial craft from 16 ft to 80ft in length in mainly steel but also aluminium. I would not count building steel boats of the size we are talking about as "heavy engineering" in fact quite the opposit it's really light weight sheet fabrication, welding sheet metal above 10 or 12 mm is easy to get good results compared to trying to fabricate from 3 to 6 mm sheet where distortion is proberbly ten fold with the lighter gauge.
the more weld that is laid down unnecessarly the more distortion is going to occur, and true welding to the longditudinals is more important then welding to the frames, infact on the size of craft we are talking about the frames could actually be removed and the hull would still be of adequate strength, but in most cases they are not and hence to much welding to them = hungry horse look.
and I have to ask if your hull is so fair then it begs the question "why some fairing was needed for white gloss finish"?
 
Thanks all contributors.

The reason for the desire to fair is because the new hull,well I beleive painted after blasting ,was constructed in small panels almost diagonal sited.Although the general shape appears good,all the joins are visible and being used to GRP it looks a bit amaterish.The fairing would not need to be very thick I feel to give a very good result, although I now take on board the movement issue. Thanks again to all .

Regards Michael.
 
Thanks for filling in your Bio.

I Assumed you were refering to me and not the origional poster as you replied to my post.

(it is always dangerous to assume as it can make an ASS of U and ME)

Having lived in Newcastle and Nottingham in thew past I do understand the weather but without a controlled enviroment timing is the key.

When I refered to "heavy engineering" I was thinking of the 3mm - 10mm thickness range not light engineering like 16 - 20 gauge sheet steel type fabrication, but having welding equipment and skill to do TIG, MIG and stick I can cover most types of welding including the fabrication of most of my own stainless fittings.

I, like the orgional poster wanted the "GRP look" mainly for resale value and if I do ding her above the waterline I could repair her anywhere in my crusing area

I agree much welding to them = hungry horse look. I was thinking of fitting water tight bulkheads but in the end did not due to the increase in weld distortion and as I said the main distortion was due to welding in extra fuel tanks and a small extension to the stern
web0727.jpg
 
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