What's your experience with power fairing boards?

Discussion in 'Boatbuilding' started by CatBuilder, Apr 28, 2012.

  1. Steve W
    Joined: Jul 2004
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    Location: Duluth, Minnesota

    Steve W Senior Member

    Cat, a 200mm DA sander is the same thing an 8" random orbit sander, i mentioned mine in post #38, made by national detroit. We also have a Fein 8" electric but they are an overpriced piece of crap, if they get set down on the pad it gets bent and then wobbles.

  2. CatBuilder

    CatBuilder Previous Member

    Thanks, Steve. Those would be for the last couple passes, to get roughness out, right?
    If you fair with them, wouldn't they just follow any unfair curves, while a long board (powered or not) acts as both a batten and a sander?
  3. Steve W
    Joined: Jul 2004
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    Location: Duluth, Minnesota

    Steve W Senior Member

    Actually the 8" is referred to as a mud hog and is used in body shops for rough fairing of filler, personally i still prefer using an air longboard and fartrock for final fairing, then the da after primer, i havnt tried the 8" for final sanding, it may have too large an orbit, or maybe not.

  4. tunnels

    tunnels Previous Member

    Fairing you need to change colours of coats of paint and hand long board if you want to get it really fair !! machines are ok but take a long time . your 2 part high builds needs to be fresh and soft to sand quickly and always put some tinter so its a differant colour !! to the layer below . you will have trouble because you spend to much time on the net !! pull the plug and get into it !!dont spot till you cant lift you arms up then you know what work is really like !!. :p
  5. pdwiley
    Joined: Jun 2008
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    Location: Hobart

    pdwiley Senior Member

    Sorry, not really trying to be a smart arse (well, not too much) but this comes up all the time on the metalworking forums.

    The USA power system *sucks*. You call it industrial power, I call it what I have connected to my domestic hot water system (240V 20A).

    I have 415V 3 phase power at 90A per phase connected to my building shed and house. I have a 415V 20A line running down to a sub-board at my dam.

    So when someone from Europe, Australia or other countries that built their grids a bit after the USA comments on yours, keep in mind that we learnt by example how not to do it. I've found that most people in the USA simply don't realise how stuff is done elsewhere and have no clue about the higher voltage, higher current stuff. Most of your 3 phase is only 240V outside special high demand industries (which figures because 3 x 115V with the corrections gives 240V 3 phase just like 3 x 240V gives us 415V 3 phase).

    Anyway, carry on..... I'm avoiding epoxy painting the keel spaces ATM so any excuse not to get back to it is a good one.

  6. Willallison
    Joined: Oct 2001
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    Location: Australia

    Willallison Senior Member

    I was talking to a very talented local (wood) boat builder at thee weekend who is currently building one of my designs. He swears by this product by Oz company ATL. The company blurb suggests that it can replace long-boarding completely.... I'm not sure if that's how my bloke uses it, or whether he uses a combination of both... but either way, he was pretty impressed with the time savings involved.
  7. tunnels

    tunnels Previous Member

    i very much doubt it !!

    The company blurb suggests that it can replace long-boarding completely.

    A little wishful thinking thats for sure ! in the hands if a inexsperianced and couldnt care less type person could be a absolute disaster and end up with a bigger mess than what they started with . If you think a little and make a decent jobs of everything the filling and high builds are not as bad as they seen and a few hours hand long boarding never did any one any harm , its sure sorts out the players and the stayers and its a good team building excise . :confused::p:D:p
  8. CatBuilder

    CatBuilder Previous Member

    Good guess, but you are wrong. Don't forget I am over 1000 miles away from home and everyone I know. I do nothing but work down here. I don't own a television. I don't drink more than one beer once a month. I work 6 or 7 days a week.

    The interwebs are my only entertainment and social contact.

    You are making stupid assumptions.
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  9. tunnels

    tunnels Previous Member

    Welcome to the world i live as well ! im 10,000 miles away from my home ! most days i start work at 4;00 .am and have a few things sorted before i get to my work place we leave at 4;30pm but my jobs goes on till 10;00 pm most every night including most saturdays to!
    As Project managing in Korea was 7 days a week most nights 3 hours to 4 hours sleep the project was 3 months late starting so had that time to pull back to finish for a boat show and the world match racing series !
    yes i am used to hard work and long hours to . our sanding and fairing at the moment is between a deck, fly bridge and hull moulds for a 95 foot lake boat . so life goes on ! The mould surface area is big luckerly lost of flat areas !:p:D:p
  10. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member


    Don't get obsessed by sanding. You fill the hull fair. With the batten. You should only be lightly sanding surface between layers enough for further applications to slide on ie the highs should be sanded. The lows should be unsanded.
  11. CatBuilder

    CatBuilder Previous Member

    That's exactly how we do it, but It's a pretty large amount of area.

    What do you use as a fill batten?
  12. mastcolin
    Joined: Jun 2005
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    Location: The Netherlands

    mastcolin Senior Member

    The power board would be great for the core fairing. I wasn't dissing it. It will get you where you want to be quick.

    We fill with aluminium extruded profiles...made for filling I think. Bevelled to a point come in 6m lengths which we cut to size. We also use specially made up ply lengths with varying degrees of stiffness. Also bevelled to point. One face is formica to keep edge and make easier to clean off filler.

    You can use L- profiles or make your own ply lengths. We sometime use plexiglass. You can bevel edge or this as well. 6mm thick or so, 10-15cm wide.

    You should have reasonably fair hull after glassing.

    Check this with long bar/profile. Hopefully you have many points touching batten, close together, not deep:) Overlap the length when checking fore to stern to keep line. Othersied you will have 2 lines with knick in join. ie if you bar is 6m long, start from 4m for 2nd check. You will see if the line runs.

    Mark the highpoints with pencil. WHen you fill only put your hand on the highs and let the filler remain off the batten in the lows. Light sand p40, very light sand enough just to rough the rough surface.
    Fill vertically.
    Repeat horizontally. You can probably (hopefully use much shorter profile now as you high points will be close together). Keep going till your time/budget decides.

    I'd board sand the filler, important areas. It is easier to sand than highbuild. Machine sand with p80 after this board sand. This will reduce risk of the board sand marks coming back after time in topcoat.

    Do a last fill with a runny mix to fill the pinholes. Just machine sand this with p80-100.

    Highbuild or 545 direct? Follow data sheet. Add the thinner, it may not look like you need it but it makes less pinholes in spray and makes it easier to sand. The 1st coat of highbuild needs to be thin. Don't ask me why but it wants to fall of the filler. Makes no sense but it is true. I have plenty of experience, trust me here. You can apply the 2nd (wet on wet) coat much thicker). Apply the required volume to get dft you want. We spray 3 coats to get 150-200micron..but this will depend on your gun set-up. You can do a coat an hour no problem.

    We board sand the primer with waterproof or dry paper (p120-150). Machine sand again p180 (see comments on scratchmarks) Board sanding will definitely take out small unevenness. It is up to you as builder to decide cost/value.

    545 sand with p280 then p360. Sand the p280 about 50% deep. Then 100% with p360. This takes out minor imperfections better (eg the orange peel from primer) and if you try to sand direct with p360 once you clean it you will see unsanded areas I am sure.

    ANy pinholes in primer can be filled with auto polyester filler. Try to fill these in highbuild before you sand, Kill 2 birds with 1 sand. Wash it down and check with flashlight before 545 stage.

    A mist coat on the highbuild and 545 to aid sanding is good idea as suggested previously. We use colour pastes and water. Sponge it on, let it dry. The colour is absorbed into the primer. Sand till clean.

    Are you using awlgrip? Speak with the area rep. He'll drop by and help I would hope (I used to be tech sales for International Paint (Interlux in USofA) in UK and I would go help people like you at drop of hat.)

    Feel free to ask for more info.

    Here is something I made earlier...

    The latest J-class in Black hull. And the underwater area is also filled fair.(no boards here:))
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  13. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Plexi makes good bog battens...its cheap and readily avaialbe. Relieve the edge. Two full sheet length battens plus a few short ones makes a good set. Alloy profiles are best if youre a Pro and have access to the stock.

    Keep the paper on your sanding board razor sharp...use light sanding pressure...let the board knock off the bumps ,burs and touch all high spots..then carefully fill the lows.

    Normally after the second bog fill you have a very good surface ready for primer then minor filling.

    Inside radius's are troublesome and need many fills . Chines, rubbing strakes and portholes also need extra attention.
  14. CatBuilder

    CatBuilder Previous Member

    My GOD this is a good thread. I just learned a lifetime's fairing experience in 5 minutes of reading. Than you so very much for these posts.

    Colin, that post ought to be a "sticky" or a "FAQ" for this website. Pure gold. Thanks!

    I will use it like a bible.

  15. tunnels

    tunnels Previous Member

    steel rules

    :idea: AS a screed for filler i use a 1 meter long !, steel rule !! its got tension ! has clean sharp edges and strength enough to hold its shape properly as you pull it across the surface go one way and then another scrape off the surplus off the ruler and re trowel that back on some where else then do the same thing again till all you filler has been used . I totally agree that thin is best ! If you run a pencil along the edge of the ruler it will leave a black mark as you bring it across the hard surface and its easy to see whats hi and whats low . If the ruler edge is really sharp it will act as a cabnet scraper and take a fine whisp of a shaving off the semi hard filler if you hold it hard onto the surface This is a easy method when doing repair work . Have a one metre rule and a 600 mm rule of my own that i keep specially for this purpose and done lend or let anyone else borrow or use . :D:p
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