Anyone familiar with an "integrated floor and stringer" design?

Hello, I am curious if anyone is familiar with or knows of any boats designed with a system as explain in this patent (US6032606A - Boat with integrated floor and stringer system and associated method of manufacturing - Google Patents https://patents.google.com/patent/US6032606A/en).

Essentially there is a hull mold, deck mold (without cockpit floor) and a floor mold. In this specific design the floor also doubles as the stringer system, being glued into the hull (and potentially glassed around the flanges) before the deck mold is jointed to the hull. The floor/string system is then injected with foam to provide further rigidity and floatation. The open cavities for gas tank and ski locker are then closed to form a solid floor by way of composite of separately molded hatches which would be affixed to the floor component spanning the cavities.

I am curious what you all think the advantages/disadvantages would be if a manufacture takes this approach? I would think they are saving on not having a separate stringer system, less components to integrate etc. Not sure what the disadvantages are, would it be any less stiff than a dedicated stringer grid?

I _think_ the 2013-2021 Glastron GT's (up to 22ft) are made like this, though I haven't torn the deck apart to find out The ski locker and bilge are 100% molded part of the deck which I think is a tell tale sign. The only other boat I can find that has the same hallmarks would be the Campion A18/545.

 

It is a cheaper way of building a boat. However, it has to be designed properly, and the fit has to be tighter than separate components. I don't see any drawback in quality. It may limit the design though.

 

Thanks for input! Only concern I have if my boat is in fact built this way, is that the carpet snaps are installed directly on the stringers and any water ingress means wet stringers. Whereas if it had a separate grid the ingress would be limited to the deck/floor core materials.

 

It’s a well known and often used method of production, enabling fast assembly time.
The thing that I don’t like about it is not having access to much of the bilges, and not knowing how well built the underfloor structure is and how well it was assembled.
You might be able to order one without the carpet snaps penetrating the stringers, or remove them and epoxy over the holes.
The new stick down neoprene? deck coatings are far superior to carpet, and require no holes.

 

Thanks kapnD! You're right, as I looked around I found more and more boats made this way, especially on the smaller end of the bowrider spectrum. I would argue you probably get the same poor visibility with a more traditional one piece fibreglass stringer grid and full liner boat? Once you place a floor on top of something like the pic below you are going to lose visibility into into anything without a hatch over it it.

 

Jimmy may be a rich man now. A lot of RIBs are done this way, some series of bowriders also. On series of sailing boats, Jimmy could have also invented the backing mold, which, in a sense, has the same principle.

Advantage ? Productivity is increased. The hull and the floors are build in parallel. No visibility issues, since you can work under the molded floors. On bowriders and RIBs, equipments are installed simultaneously on the hull and on the mold. Let some hatches be used to connect cables, fittings were the molded floor and the hull are glued together.

Drawback ? Since every mold has a cost, you'd better be sure to produce a certain amount of boats to use this method. Second, if the molded floor and the hull are not properly glued (surface preparation, glue mix, glue thickness, backing mold positionning...) you get an additionnal risk of structural failer.

 

As it turns out Jimmy J Fulks is the founder of Mariah and this was their big push around 1998-2000. Apparently he ended up suing a bunch of other manufactuers who know have their name on the patent as well...assuming they reached some kind of licensing agreement.

If you take RecBoat holdings as an example, they also manufacture FourWinns which is a full liner boat and would have 3 molds; hull, deck (full liner) and structural grid. Whereas their Glastron line would have three different molds; hull, deck (without floor) and integrated floor/stringer. 3 molds in both cases, that said you could argue the full liner deck and potentially structural grid in the FourWinns would be more labour intensive than the simpler deck and floor/stringer in the Glastron.

 

Thanks for these details, @brg7910.
When It comes to surface complexity of decks, designers and architects are sometimes very prolific Indeed. While manufacturers tend to be more rationals. For reasons, of course.

As a matter of fact, there are quite a bunch of parameters driving choices in boat building. One off GRP boats around 30' have, in general, only 2 molds. One for the deck, one for the hull. Floors are replaced by frames and stringers. Not to mention the "flat panels" building method, that could be employed for various boat size, small number of unit per year. No molds, but marbles, bulkheads, porques, molded floors without liner.

Also, in conjunction with the boat marketing, boats can also simply be built in metal. Again, no floors, no molds, but frames and stringers. Weight trade-offs are generally acceptable, and some other advantages can also be put to the front.

As far as I know, chasing costs is essential, and, from my experience, liners (hull, deck) are more commonly found in medium production and above, say above 10-15 units per year.

 

I've been involved in patent litigation for composites, there isn't much new in the last 70 years, most ideas and methods have either been patented or in common use since the 1940s and 50s.

Although people patent stuff every year thinking it's new, or at least trying to stop others from using the method. But if you actually do good research the method it was probably patented a very long time ago.

As for a combination liner and stringer grid, it's been used in some way shape or form since the late 1950s that I know of, and probably much longer than that.