Have I just ruined my boat ?

[Dave-Fethiye]

Yesterday I sanded the hull of my 12m wooden boat. I am new to boat repair as this is my first boat.

Everything seemed to be going well - I used my grinder with the sanding disc attachment and a no. 50 sanding disc (well 10 of them).

It was only when I was putting on the primer coat that I realised that the surface is covered with flat "facets" rather than being a nice smooth convex shape.

I finished putting on the primer coat as I wanted it protected from the sun and heat ( here in fethiye, Turkey it is 48 C ).

So, I think that I have just discovered that there is more to sanding a boat that I thought !

Can this be "fixed" ? Should I hire someone to re-sand the boat to get back the nice shape - is that called fairing ?

I'd appreciate your comments and help, I am feeling a bit low !
Thanks.

[knottybuoyz]

What you need to get/make is a "long board". It'll look something like this.



You use long sheets of sandpaper and make long strokes (elbow grease required). This will help you fair out the flat spots left by the circular sander. You can probably make your own out of a pice of 1/4" ply and a couple of old doorknobs. 3M77 adhesive works well to hold the sandpaper on. Make it as long as you can comfortably use because the longer the better.

There are pneumatic versions as well.

[SkiprJohn]

Aloha Dave,
Yes, its called fairing. Many boats have the facets you have talked about because owners use what you did to sand their boats. A more appropriate tool would be your sander/grinder with an 8" soft pad and 120 to 150 grit to get rid of old paint.
At this point a long flexible board with a long piece of sandpaper from a belt sander glued to the bottom might take most of the wows out if they are not too pronounced. If they are really bad then you might want to use filler and then the long board (fairing).
Send us a photo and some other folks might have another suggestion.
Kind Regards,
JohnL

[SkiprJohn]

Rick, You beat me by two minutes.
Dave, Make certain the board flexes to the contour of the hull.
JohnL

[roverhi]

Never ever use a grinder with the hard rubber pad on anything you want/have to look at afterwards. If you must use a grinder, and I do a lot, get the 8" or so foam rubber pads, that replace the hard rubber pad, to which you glue a sheet of sand paper. The foam pad allows you to run the sanding disk parallel/flat on the surface and floats over irregularities sanding down the highs and leaving the lows. It's relatively easily to get a smooth even surface and take off a lot of material quickly. It is possible to gouge but you have to be pretty ham fisted to do it with the foam pads.

FWIW, I've also glued an 8 1/2" plywood disk to the foam pad and glue the sand paper to the plywood. On flat surfaces, this works like a drum sander/planer, and about $500-$2,000 cheaper than buying one of those expensive tools.

One last thing, get a grinder that turns at 3,000 rpm or less. They are usually advertised as sander/polishers at that rpm. The lower rpm won't burn and melt FRP as you sand and are a lot more forgiving of inattention on any material.

Aloha
Peter O.

[Alan Wheeler]

Dave, don't panic as yet. You are only half way there with your process. At thi point, the next easiest step to take is to use a high build undercoat. You then long board this to smooth off the surface and contour it. If the hull were Glass, you would use fairing compound, but it really isn't neccessary with timber. So you paint it on, sand it off with a long board and paint on some more and repeat till you get the smootness you want to achieve. If the hollows are very deep, then a fairing compound maybe your best bet for extra high building of the hollows. But no, you haven't ruined the hull. It's long hard work and one major reason why you want to use a very good paint system that lasts. It may cost more, but you only want to do this as least often as you can.

[Boracay]

Bringing a boat into perfect condition is a much overrated pastime.

If I understand your previous posts this is not an expensive boat.

If you are mainly interested in getting the boat into seaworthy condition then there is no need to fair and smooth the hull. In fact excessive fairing could take too much off the planks.

Water flow along the hull will be very little different.

The rough surface left by the grinder should give a good key for the paint.

I would suggest a light sand (course paper, ideally used lightly by hand with a rubber backed sanding block) after each coat ( but not on the final coat).

Using high build paints will give a good paint thickness.

[44'cruisingcat]

If you want to get it fair, than as has been said, a longboard is the way to go. The longer the better too - if you can get someone to help you with it, make a two-man board. There's a builder in Brisbane who has a 3 man board!

[dana-tenacity]

I was tlking to a professional last week who is facing longboarding a 100' mega yot. They are using six foot torture boards.

[cat man do]

Originally Posted by dana-tenacity

I was tlking to a professional last week who is facing longboarding a 100' mega yot. They are using six foot torture boards.

First 2 year's of my sentence at "Lloyd's Ship's" in the '80's was doing exactly that.

http://newimages.yachtworld.com/1/5/...?1161372769000

Overhead doing deckhead's was especially pleasurable....................NOT.

Don't call 'em torture board's for nothing.

Dave

[delmarrey]

Welcome to the school of hard knocks.

If you had a steel boat, all would have went well. But seeing that your boat is well seasoned it doesn't really matter too much. Just chalk it up as experience. It's better to learn your mistakes on a project boat then a new one.

Some of us here have been working on boats for more then 40 years and not using something like a grinder disk would have been common knowledge amongst us.

Myself if I want to take off large quantities of paint I use chemicals and a scraper. Then finish up with a large orbital sander. They won't dig in unless one gets crazy with it.

If anyone notices all the little crescent marks, just tell them it is a textured finish of a Muslim design.

[cooper]

Here is a section of an article on fairing that l wrote recently for the MBS quartely............... Due to the fact that l am going to sand, the wind will have arranged itself to blow in the general direction of my face. That is of course unless l am sanding from underneath, in which case there will be no wind. Donning the usual armour l then do my warm ups, breathing exercises and meditation, for l am about to use “The fairing board”. This diabolic piece of equipment consists of a flexible board about 700 mm long with a handle at each end. Covered on its surly underside is the coarsest grit sand paper your already aching body can handle. (In my case 80 grit.) Mine is made of masonite and the sand paper is attached with contact cement. You then attempt to remove filler in a precise and even manner to your desired level. This is to be blunt; impossible. The tiny amount of dust removed is neatly transferred from the hull to your ears. This has the curious effect of turning your arm muscles to jelly and back into spasms. After absorbing this punishment for a more than reasonable time, the power sanded is brought into action, allowing for a speedy series of uneven bumps and holes to be produced. This in turn requires the process to be repeated from the beginning. .........have fun. ; )

[cat man do]

Originally Posted by delmarrey

If anyone notices all the little crescent marks, just tell them it is a textured finish of a Muslim design.

Not that there's anything wrong with Muslim's , eh Del.

Dave

[cat man do]

Originally Posted by cooper

Here is a section of an article on fairing that l wrote recently for the MBS quartely............... Due to the fact that l am going to sand, the wind will have arranged itself to blow in the general direction of my face. That is of course unless l am sanding from underneath, in which case there will be no wind. Donning the usual armour l then do my warm ups, breathing exercises and meditation, for l am about to use “The fairing board”. This diabolic piece of equipment consists of a flexible board about 700 mm long with a handle at each end. Covered on its surly underside is the coarsest grit sand paper your already aching body can handle. (In my case 80 grit.) Mine is made of masonite and the sand paper is attached with contact cement. You then attempt to remove filler in a precise and even manner to your desired level. This is to be blunt; impossible. The tiny amount of dust removed is neatly transferred from the hull to your ears. This has the curious effect of turning your arm muscles to jelly and back into spasms. After absorbing this punishment for a more than reasonable time, the power sanded is brought into action, allowing for a speedy series of uneven bumps and holes to be produced. This in turn requires the process to be repeated from the beginning. .........have fun. ; )

Pussy,

I thought STANDARD torture board paper was Roadbase, then 36 grit.

80 grit's for fairing the Highbuild.

Oh and Rick, those pic's are short board's, they are long board's when they get to 3 ft plus.

Dave

[delmarrey]

Originally Posted by cat man do

Not that there's anything wrong with Muslim's , eh Del.

Dave

I hope you weren't pulling something out of nothing.