Fairing the hull

Well, it’s been 4 years since I last worked on my Marblehead and 4 years since I’ve been on one of these sailing forums. I see that Doug and Dick are still there.

Anyway, I pulled out my Carbon fiber Marblehead Hull and made a new fin and finished the deck and now it’s time to paint the hull. One problem. the hull sure has a lot more ripples in it than I remember.

So what’s the best way to fair the hull? What are you using for filler?

hi there
i am not sure what you meen by ripples? but i have always like using epoxy and microballons. it make a water tight joint, and is sandable. if you are doin gthe deck to the hull . i would just use the epoxy. then go to the epoxy/microballons. to fill the low spots. you can use autobody filler. but it will absorb water from time to time( sorry for the spelling). i hope this helps
long live the cup and cris dickson

Filling a lightweight hull can fly in the face of what you are trying to do. Depending on where you are heading with your boat, I guess the first thing to ask would be what you hoping to achieve. If you want a lightweight hull, then you don’t fill anything, and try to work in the other direction as to what you can take off to make it lighter still.

if you are looking for a boat with greater emphasis on appearance, and performance is
#2 then you would fill and sand as needed.
If you are trying for both, then I would probably have to cast a new hull and start over.

I have several composite hulls of different methods that have been laying in storage for a couple of decades and they have not lost shape, so I am uncertain as to what the cause would be with yours, but if you can… you might want to identify it to make sure that it is not something that is going to come back again!

I use “feather fill” which is an old product that you spray on.
An alternative to the above mentioned microballoons is mixing your own blend of resin and talcum powder. In airplanes it was clear dope and talcum, but resin would work better for you. Sometimes depending on the consistency that you need, or chose… you may want to thin it with acetone or Interlux solvent. Not knowing what the size of the irregularities are, it is hard to say. You can also use fiberglass sanding dust to mix with the resin.

We never have a shortage of that around here and it works quite well. The difference between a glass hull and a graphite or kevlar hull is only a few ounces… and resin weighs only a few ounces… so temper the amount that you put on.

By ripples I meant that the surface was wavy with a lot of high and low spots. Kinda like cellouse on Rosie’s backside. [:)][;)] I want to reach some compromise between looks and performance. Running my hand over the surface makes me think that the manufacturer that I bought the hull from handsanded the plug instead of using a sanding block.

What gives better performance? A glass smooth hull or saving a couple ounces?

I looked up featherfill (www.aircraftspruce.com) and it looks like it may be what I need. I also have a can of “Ultimate Bondo” here whose main ingredient is talcum powder.

So what do you guys use to sand (fair) down the hull?

Unfortunately, I think something is very wrong with the hull you purchased.

Most molded boats, particularly carbon fiber, are “fair” right out of the mold. They are symetrical and do not have waves or ripples. Many are sailed with simply a clear coat over the carbon; if painted they are first primed and then given a color coat. I am not aware of any that are coated with fairing compound.

It would seem that the ripples you see in the hull suggest a defective layup or that something happened to the hull during storage. It would seem likely that the hull will continue to deteriorate over time.

In all events I would think the best thing would be to start over with another hull. I’d try to contact the builder, explain the problem and see if you are offered a replacement.

Don’t use bondo or polyester based thickened fllers because they could shrink and further distort the hull. Aircraft Spruce has a veryliteweight epoxy based filler.
But trying to fill and sand an already thin hull and wind up actually improving t e hull is very difficult because no matter how you go about it you will be, at some point, sanding two different densities of material. If the imperfections are too much for feather fill then I’d seriously consider another hull unless racing is not important. The labor and the results probably aren’t worth it if it’s “bigger” than feather fill…

Doug Lord
–High Technology Sailing/Racing

My particular boat has a gel coat. I went back to the original website where I bought the hull and took a look and in the picture of his boats, I could see the exact same waves in the surface of his boats that he had for display. Decided not to bother contacting the guy.

So before I drop another couple hundred bucks on another hull, I decided to order Featherfill and try it out first. That way, if it doesn’t work or look good, I’m only out $19.

Just so I know, who makes a decent Marblehead hull??

Next question, How much does a competive Marblehead hull weight?

Go to amya.org and to Classes where you could get the Marblehead Class secretaries’ e-mail address; you might also try the Windpower site under “Ask the Expert” where I think Jon Elmaleh’s e-mail address may be listed or you might be able to PM him.
You could also PM Roy Langbord who has contributed here and sailed Marbleheads for a long time.

Doug Lord
–High Technology Sailing/Racing