Bottom layup

[xanadu]

I would like to find out if anyone knows how Hatteras laid up their boats. After doing work to the bottom of my 58YF it looks to me as if the hull was laid up in a mold and when removed additional layers placed on the bottom. Would that be a good guess as to how it was done? I am also trying to figure out how many layers of glass make up the bottom of this hull.

It looks like two different types of resins were used so possibly the PO did work and added layers I am not sure. Whatever work was done before, the person doing the job did not remove all of the moisture and as a result, there was some serious damage to a couple of the layers which has now been removed and dried out completely.

Don't want to rush the job but am anxious to get her on the water.


Alan
"Xanadu"
1974 58YF
Trinidad and Tobago.

 

[jim rosenthal]

AFAIK the hull is laid up in the usual fashion- gelcoat (two layers, different colors) sprayed into the mold, then the layup done by hand with sprayed polyester resin. Hatteras yachts were not vacuum-bagged or anything like that until recently. I have never seen any chopper-gun fiberglass in a Hatteras, but I haven't looked at all the boats, either. My last visit to the factory was when it was still in High Point.

 

[REBrueckner]

Alan,
This is one of those complex subjects, and as you probably know, one with too many jobs with unhappy results.

Depending on what you want to know, how much detail, you could call Sam's....I'll bet somebody there knows the original process, or maybe Roger Weatherington....who posts in this forum.

I did not know the older Hatts used gelcoat...I was told my 1972 48 YF was not gelcoated but painted....never investigated. I do not know what "gelcoat" actually means....but it can in general be epoxy or polyester. They reportedly did NOT use chopped strand, but rather fiberglass cloth....thats the "hand layup" Jim posted.

Likewise, bottom barrier coats used to be epoxy or the vinylester version...both were available.....may still be.....be sure to check to see what has proven best.

I just checked and one brand is still around, Interprotect 2000, with some good general information here:
http://www.wholesalemarine.com/p/IL...0E+Epoxy+Barrier+Coat+Kit,+Grey.html#readmore

Also note the Petit Protect primer advertised on the right....is a primer like that worth it....another good question for "expurts".

Hatteras did use polyester resin, and subsequent repair work to my knowledge must be limited to some type of epoxy resin, for adhesion, like "epoxy" or vinylester resin. As I understand it, once polyester resin dries, additional polyester makes only a weak bond...poor adhesion in other words.

All I know about vinylester is that it is generally low viscosity compared with "epoxy" resin. Best to find out from experts what resin to cloth material ratio is now considered best for the kind of repairs you have planned...and there are MANY different cloths available. Some yards like vinylester resin to flow into cracks.

Any "bottom coating" that was done subsequently should have been designed for that underwater application. Adding more polyester resin and fiberglass cloth for build up to replace original layers that were removed is NOT the way to go.

Good luck.

 

[Boatsb]

gelcoat is sprayed into the mold as the first outer layer. I do not know about 2 coats but I doubt it as gelcoat is there for 2 reasons. 1 color and 2 smoothness. If it was being painted (all hatts except i think the 32's were painted) there was no reason for 2 coats nor would having thicker gelcoat be a good thing as it cracks easier.

As far as adding glass after it is removed from the mold I would say that after removal from the mold it was put in a jig.the stringers and supports were attached in the mold or jig and any additional layers you are thinking of would be attributed to adding bulkheads and other items.

REB Epoxy will stick to most any other resin but nothing but epoxy sticks to epoxy therefore if you are not sure you use epoxy. I like polyester myself and use it when I can. Epoxy only when I need to.

 

[REBrueckner]

"Epoxy will stick to most any other resin but nothing but epoxy sticks to epoxy therefore if you are not sure you use epoxy."

good point I forgot....

 

[67hat34c]

Hats were always molded with Gel Coat then painted out of the mold. I believe all layups were done in the mold. I was told that they use to pull the boats out of the mold and if they flexed, they dropped them back in and added more glass. They did not understand that it was ok for a boat to flex. Was told this is the reason why no 2 older hats of same model weigh the same.

 

[xanadu]

Thank you for all the comments.

I removed 3 layers of old delaminated glass (mat and woven) that also looked like it was not completly wet by the resin (as seen by dry glass material) and am replacing it with Biax glass material and west epoxy resin. Having taken off the three layers of old material, I reached a surface that was solid and smooth with two different color resins and looked like it came right out of the mold like that. If as said, that all material was laid up inside the mold I am assuming by what I see that the PO did work and added some material layers on the bottom.

One thing I do know is that when it is finished it will be solid and we could cruise in confidence.

 

[Angela]

I was taught that polyester resin is never to be used below the water line. Is that wrong?

 

[REBrueckner]

Angela: Hatteras used it, original, but subsequent polyester has poor adhesion for structural integrity once under layers are dry....

 

[67hat34c]

Poly is used on almost all boats due to cost. Vinylester resin is a much better alternative and has similar qualities to epoxy which is the best. I think hinkleys use vinylesters as do some other highline composite manufacturers.

Problem is that Hatteras was notorious for using cheeper materials than Chris or Bertram. That is why the Hatts blister--refer to Pasco for better explanation.

 

[Avenger]

gelcoat is sprayed into the mold as the first outer layer. I do not know about 2 coats but I doubt it as gelcoat is there for 2 reasons. 1 color and 2 smoothness. If it was being painted (all hatts except i think the 32's were painted) there was no reason for 2 coats nor would having thicker gelcoat be a good thing as it cracks easier.

My understanding is that they sprayed in a layer of white gelcoat for smoothness and mold release, (and obviously it's an easy color to paint over) then a layer of black to keep light from showing through and making the hull appear thin.

Or something like that.....

From the Hatteras website:

From the waterline down, Hatteras uses both a vinylester blister-resistant gel coat and vinylester resin in the skin coat. This process provides additional blister resistance and reduced water intrusion.

Hatteras utilizes two other gel coats: an exterior white gel followed by an interior black gel. Both gels are resin-based. Application of the black gel provides a dark backdrop that improves the fiberglass lay-up quality during construction.