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Author Topic:   Calling all engineers....
here fishy posted 05-09-2000 11:30 PM ET (US)   Profile for here fishy   Send Email to here fishy  
I previously posted a question about securing relatively large objects to the deck of a 13 ft. Boston Whaler. The large objects in my case is a small wood center console which came with the boat when i bought it, and a wood box that I just built which houses a 12 gallon gas tank and will also serve as a seat. Boston Whaler recommends securing only to the plywood located in specific areas under the deck. The wood diagram is clear however the wood is minimal and the location doesn't correspond with what I'm trying to do.

The center console was loose so I removed it and discovered that the previous owner glued the 2x4 wood inner cleat to the deck with 3m 5200 and 12 brass screws. The 5200 was used sparingly (like a quick swirl on each 2x4)
The brass screws didn't hold and the holes widened over time, therefore loosening the whole thing. Will generous amounts of 5200 and wider screws make a big difference?? I say probably not and that's why I'm concerned and seeking opinions.

I think his method may have lasted about 18 months. Truthfully, I could have left the console on as it was for a few more months but I know it would've loosened eventually. When I got the idea to build the box/seat I started looking at the console closer and discovered that I could move it enough to do something about it. The console itself is very solid but he didn't put much effort into securing the thing down properly.

I've built the box out of the best 3/4" grade AA marine plywood and did the whole stain, West epoxy/hardener and marine UV varnish routine. The box is now complete with an inner wood cleat of 2x4's mounted with stainless "L" brackets to the inner walls of the box. The console also has a new inner cleat with similar "L" brackets. In
retrospect I probably should've built the box and a new console out of 1/2 or 3/4" polymer sheets (King Starboard-Marine Grade Polymer). Saw it in Cabela's and could probably find similar stuff locally. But, whats done is done.

With both items finished and ready to go the challenge is to secure them as well as possible.

I have some ideas swirling in my head from what has been shared with me but haven't decided on anything final. I'd like to find the best home made solution and try to pull it off myself but if the final solution requires professional service, I'll bite the bullet and pay someone to do it right, especially if it involves fiberglass
matting/sheeting etc..

As I've mentioned in the past, my expectations and plans for a boat of this size are realistic. No hot dogging, just
very local fishing within a mile or two offshore conditions permitting but mostly inside the walls.

Any and all suggestions/ideas would be appreciated including recommendations to professionals that might specialize in this sort of work. (Southern California-Los Angeles)

Thanks to all for your patience and I look forward to the responses.

kent posted 05-10-2000 01:33 AM ET (US)     Profile for kent    

I am facing a similiar problem with the attachment of side rails to my old 13 foot Whaler. I have posted twice about my problem and have not received any responses. Apparently, there is no wood in the gunnels of the older 13's so basically I too have to make attachment to the fibreglas.

I think that I may have come up with a way to provide anchorage for my rails, and it may work for your application as well. I am thinking about getting a stainless coupler, the device used to join two pieces of threaded rod together. This device is about one inch long, is threaded, and is hexagonal on the outside. I will drill a hole slightly larger than the coupler into the fibreglas into the foam. Then I would put epoxy into the hole and set the coupler into the epoxy, being careful to insure that the threads of the coupler are protected. This would create a "plug" of epoxy around the coupler and the fibreglas. Since the coupler is about one long, there should be enough surface area on it to form a good bond. I would then screw the stanchions of the rail to the coupler and the gunnel with stainless machine screws. You could probably do something similar using L brackets.

I have another method that I use to attach grab rails to fibreglas shower stalls that involves using a PVC plate that I fabricate and epoxy to the shower wall, in order to firmly attach the grab bar. This method is not the prettiest for my side rail installation, but it would probably work for your console and seat, as you could hide the PVC plates.

If all this is as clear as mud to you or you would like more information on either method, I could provide further info and a sketch to illustrate. Just e-mail me to let me know.

lhg posted 05-11-2000 09:51 PM ET (US)     Profile for lhg    
Fishy: It appears you have a serious problem on your hands, since as the diagram shows, the only wood in the floor of the 13 was where the vertical leg of the side console screws into the floor. All seats in 13's are meant to be thwart seat style, spanning across from the wood blocks in the ledges of the sides. Somehow your center console control box has got to be anchored to that one piece of plywood in the floor. As you have seen, nothing else works, and you risk destroying the inner hull integrity by delaminating the floor from the foam.

Regarding side rails, if they are by Boston Whaler, they need two attachment points, the base and the side support stantions. There should be wood definitely in the ledge where the bases screw in. Later models had wood pads located in the sides for both side and bow rail supports. If you catch the light right, you can often see these areas under the fiberglass. If there are none, Whaler had a special thru hull ss casting that was used, looking like a double "T". The top of the "t" is a plate about 3/4" wide x 3" long and has threaded receivers (double legs of the "T") for the rail plate screws coming through from the inside. It's basically a compression fitting, spreading the screw load across the outside glass skin, securing the rail by using the thickness of the hull for support. One has to be careful tightening down the 2 screws to not over compress the glass, causing delamination inside or out. The bow rail on early Nausets was secured this way, and it worked quite well. All these resin plugs & molys that have been used are bad for Whalers, since as you tighten down into them, they tend to lift the glass skin off the foam, which can result in major hull failure at worst, or a spongy floor at best.

lhg posted 05-11-2000 10:21 PM ET (US)     Profile for lhg    
Further to the above message, these through hull rail compression plates can be seen in the picture of my 1971 Nauset in the 16/17' reference section.
kent posted 05-12-2000 04:04 PM ET (US)     Profile for kent    
I would not use the double T- shaped fitting that Larry is talking about. The old rails on my 13 ft. were attached using these fittings. In my opinion, it is a very poor method of attaching the rails. It is a compression type arrangement, with the inside and outside skin and the foam being sandwiched between the T fitting and the rail stanchion. It depends on the foam to hold the fitting and the stanchion apart. What happens is that the foam compresses, leaving a substantial and very unsightly dimple around the fitting on the outside of the hull and around the stanchion on the inside. On my boat, these dimples were about 3/8" deep. As Larry suggests, the foam did not delaminate from the fibreglas. The damaged areas were quite sound, just compressed. It is no wonder that WHALER did away with this system.

As far as epoxy plugs are concerned, there are many variations used. It is common practice that is used by many people with great success. The usual method is to drill a hole through the fibreglas and into the foam that is larger than the diameter of the screw, fill the hole with epoxy, allow it to cure, drill a pilot hole in the hardened epoxy, and then insert a wood or self-tapping screw. My variation on this would be to use the coupler as described and use a machine screw. While this wouldn't be recommended for attaching LARGE objects to the hull, it would work fine for smaller items. As you may or may not be aware, the foam filled hull concept is not unique to Whaler. There are actually quite a few companies making similiar hulls. Owners of all these boats usually want to attach hardware to their boats, everything from antennaes to downriggers and outriggers, bait stations, and fish boxes, that the manufacturers have no way to know about, and can not possibly place wood into the hulls for attaching aftermarket items. The plugs are widely accepted, and they do not compromise the hull or the foam at all.

Regarding the attachment of LARGE items to the hull and the idea that the only way to do this is to screw the item to wood pieces placed under the skin is not correct. The method that I would suggest using the PVC plates are basicaly the same, except that the PVC plate is bonded to the hull on top of the skin whereas the wood is attached to the skin underneath. To say that the hull would be jeopardized because the fibreglass could be pulled away from the foam doesn't make sense. The pieces of wood that WHALER used in the hulls for backing were quite small, only 1/2" thick and 2"X2", 3.5"X12", etc. The pieces of PVC material that I suggest would be sized similiarly. If the force on an object was such that it would pull the fibreglas away from the foam if it was attached to a PVC block on the top, then it would certainly pull the fibreglas and the small piece of wood that WHALER used under the fibreglas away from the foam as well. The PVC material that I am talking about is 1/2" thick and is a much superior product for fastening to than plywood. It does not rot and screws will not come loose in it.

I think that WHALER intended their boats to be customized. This is evidenced by the many applications of WHALERS to military, law enforcement, and commercial use. If you look at any of these type of boats, they are usually heavily modified and have all kinds of equipment attached to them. It is inconceivable to think that anyone could anticipate all the modifications and equipment that would or could be attached to a boat in it's lifespan used for these purposes and have the manufacturer place little pieces of throughout the hull when it was built so there would be a "proper" place to attach to. Yet, these boats have equipment added and taken away, and they are used hard, and they seem to fare well. The hull is not jeopardized, the foam is not harmed.

Unless your WHALER still under warranty, I would not be too concerned with " going by the book", or their manual as it were. Keep in mind that WHALER would probably want you to leave the hull completely alone and not attach anything to it. It can complicate warranty claims. That being said, I don't think that WHALERS are as fragile as some of us may think.

FISHY, if I were you, and I wanted to put the centre console and seat in, I would just go ahead and do it. It may not be WHALER approved, but I think you can find a way to do it and be happy with it. Just use some good old common sense.

BD posted 07-25-2000 07:37 PM ET (US)     Profile for BD  Send Email to BD     
Just a quick note on use of double-T fitting for through hull should work fine if it has a sleeve to maintain the original width of material.
JimU posted 08-04-2000 05:22 PM ET (US)     Profile for JimU  Send Email to JimU     
To fishy: Go to marine west and pick up the west system manual on fiberglass repair. It has a section on how to attach hardware if you have no supporting material behind the fiberglass skin. You might consult their website or go to the website of Interlux.It also has some related info. good luck. JimU

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