Two Piece Hull Laminates

[Pete]

Not sure many HOF members read Passagemaker Magazine, but I read it cover to cover each issue. Yes, focused on us slow boats, however some great articles. In the June issue on page 68, part of a review of a Krogen 55, reports a company representative was making a point that they lay up the entire hull in one piece as opposed to other boats that lay up each side (half) of the hull and then join them later in the process. Last I heard of this type of lay up was back in the 60's when I was told that Chris Craft Commanders were done in two pieces.

Can not believe in this era of lighter and lighter lay up schedules some boat would be built in this fashion. Does anyone know of a manufacturer that is doing this? Must be some competitor of Krogen, to cause the representative to brag about their superior process.

Pete

 

[Walter P]

Pete,

The very first Hatteras and some of subsequent models were molded in a two piece mold. Now because the mold was two pieces, the molded product (Hull) was in fact one piece. The two halfs of the mold were fastened along the center line from the tip of the bow to the top of the transom making it essentially a one piece mold. After the newly laid up hull was cured, the two halfs of the mold were seperated to release a nice new one piece hull.

Chris Craft actually went one step further and had a three piece mold that produced a one piece hull. Check out one of the older (late 60's to probably mid 70's or so) Chris's and it becomes apparant that it was the only way to achieve their hull design with a molded in full length spray rail and still be able to release it from it's mold.

While other companies probably used the same technique, it soon became apparant that it cost more to make a boat that way rather than with a one piece mold. Too bad because some of the older designs were really beautiful. Take a carefull look at the hull from stern forward of an early
model 38 MY (1968 +) and notice the graceful tumble home on the stern. I don't think it would be possible to achieve it or the details of the early CC's that I mentioned above with a one piece mold.

I doubt that anyone makes a two piece Hull, but they make a one piece hull with two or more mold pieces.

Walt

 

[Pete]

Walt, I agree that many manufacturers have and continue to use split molds, that are bolted together during layup. In the case I noted, the process is reported to include actually laying up the two hull halves with the mold separated and then bolting the mold together and doing a secondary bond along the center line of the hull. That is what caught my attention. Another item that caught my attention was the information that Krogen uses fiberglass encapsulated mahogany as hull stringers. My opinion is this is a terrible idea. If you are going to use wood then this is where you use plywood. I suppose that mahogany sells a lot better than plywood in the brochure. The Hatteras stringer design is the right answer. I would not even consider buying a boat with wood in the hull stringer system.

Pete

 

[Walter P]

Pete, I'm not familiar with the bonding process that you describe, but I suppose anything is possible. I can say without doubt that I personally would not walk away from such a design, I'd run like hell.....no matter what "wonderful" company designed and built it.

It seems that the more I see and hear about various boat builders procedures, the more I like about Hatteras. With very rare exception, nothing comes even close to the quality of design (mostly Hargrave) or execution of construction of a Hatteras. If I was in the market for a new boat in the 40 - 70 ft class, I would buy an older Hatteras, tow it, drag it or run it to a reputable yard like Slane or Jarrett Bay (I'm sure there are others as well). Have it completely gutted and rebuilt from scratch. Even if it cost close to a brand new factory product with today's alledged "superior" design, it would be well worth it.

Of course when our current worldwide financial debacle finally ebbs and people start buying new boats again, I would hope that Hatteras gives some serious thought to going back to their roots. If you have a winning game plan, why change for the sake of change.

Walt