glass stanchion bases

Is anybody out there building them?

I am beginning to mull the possibility, but have some questions, like how can you tell if it is strong enough? How would you set up a home test that could tell you anything? Oh, and how would you design and build them?

My project is a 36' Kurt Hughes beachcat in cylinder moulded plywood, with balsa decks. In the US. I may or may not get it Coast Guard certified, but if I do, I would not want to have anything that will cause too many problems with the process. I got a laminate schedule from Kurt for composite chainplates, and I am assuming that as part of the process they would be submitted to the coasties along with the other plans. Does anyone know how the USCG handles such unconventional stuff as composite stanchions? Maybe I would have to get something engineered and drawn up special? Or does anyone know of any "stock" plans?

I have never seen these animals and am totally ignorant, but my vision of how they would come together would be to either lay up some tubular stock for the stanchions themselves, or buy some SS tubes and use them as molds for the bases, laying up some sleeves on them, then cut to some length (?) it seems like taller than storebought stanchion bases would be better, and some how flare out the base part,while wet, perpindicular to the base, and reinforce the tube/base junction with a flat plate, that has been laid up seperate, probably wrapping the whole thing up and glassing (bagging?)

So then would you glass the whole thing flat to the deck? through "fasten" with some tow fabric, or not?? Or am I not thinking far enough "outside the box"?

 

A lot of the ultralight keelboats built in Santa Cruz in the 1980s such as the Olson 30 and 40, the Santa Cruz and Express lines etc used molded in glass sockets with regular ss stanchions, a much better settup than the standard bases as they protrude through the deck down the inside of the hull and are glassed to both.

Steve.

 

Composite stanchions are showing up on aircraft carriers. One of the stated advantages is that they are easier to re-use when bent from an impact. I wonder how that works...


http://kazakcomposites.com/ship-structures.html

edit- hers's more..
http://higherlogicdownload.s3.amazo...025-2012 Fanucci-Crane Abstract 9 13 2012.pdf

 

Evidently in the past some rules commitees considerd carbon fiber stanchions unsafe due to sharp splintering upon failure....

http://www.yachting.org.au/site/yac...07 Proposed Amendment 11 - Stanchion CESR.pdf

 

Although the site is in Dutch, Julius speaks/write excellent English

He is building one of my 32ft Eclipse catamarans and recently did some tests on glassed in place stanchions. The results were not quite what we expected - stanchions are not as strong as you might think

I suggest you contact him direct

http://www.albonham.demon.nl/

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Here is a picture of one, so somebody's doing it. It looks simple enough.



http://www.f-boat.com/pages/news/Sayerf41.html

 

Thanks Richard! I dropped him a note

edit
by the photos on his site it looks like he made a square base with a vertical solid glass rod that fits inside the metal stanchion (as opposed to a sleeve on the outside) and glassed that to the deck sample. It does not appear to be thru fastened. Then he wedged it to the overhead of his shop and tied off some weights to a line that is hung from the top part of the stanchion pulling on the end of the "lever". It appears that the glas base held up fine, and the ss stanchion bent.

For those interested, the photos are in the 2012 folder, listed under "railing"

 

I would build the bases out offiberglass as done on the Santa Cruz boats but use thicker walled aluminum for the stanchions with a larger diameter, a molded in socket where you can glass to the deck and hull with no fasteners just makes for a more rigid leak free settup,you could start off with a piece of G10 tube or make your own around a mandrel. It seems to me that the weak point of the stanchion itself is where it exits from the base because the wall thickness is so thin, aluminum is 1/3rd the weight of ss so if you maintained the same 1" diameter but doubled the wall thickness, it would i think take more force to to fold over the aluminum one. You could have the aluminum ones anodized and they would look quite nice, would not be tapered though.

Steve.

 

i recently viewed masalai`s boat (another forum member) and he had glass rods as stanchions. I didnt ask him about the bases and to me i could not see anything, so they may have been directly glassed to the bulkheads in the hull. Anyway, the solid glass rods were flexible... you could bend them by hand - although it took considerable force. The idea is, they dont break, they simply bend a bit when loaded up, and then spring back afterwards. Masalai described an incident whereby one of the stanchions got caught on something when docking at a wharf. The stanchion was severely bent and he thought it was going to break off, but it simply sprung back again once the snag was cleared.

So with solid glass rods, i think there is good merit to use them except the weight penalty... hollow glass tubes im not so sure as they would surely get broken much more easily. Hollow tubes with stronger stanchion bases making replacement simpler is certainly an option for a light weight solution. Id be tempted to glass solid glass rods to the bulkheads in the hull and use them as stubs for slip on tubes from above deck. No leaks or complex molds to make this way and very strong connection to the tube. IMHO they do look nice as opposed to metal balustrade, esp aluminium once it powders and corrodes or bubbles the paint, looks rough...

 

I wouldnt glass the stanchions in permenantly because they are going to get broken sooner or later. I think the solid glass ones are too heavy otherwise fine. Aluminum if anodised holds up well, typically the corrosion you get on masts and booms is around fasteners and ss fittings. Glass tube may be ok if the wall is reasonably thick.

Steve.

 

Here is a link to an article about composite chainplates.

http://www.duckworksmagazine.com/12/howto/chainplate/index.html

It may have some info that applies here.

 

Julius, the builder of Richard Wood's Eclipse e-mailed me back and explained how he built his stanchions- He used 22mm dia, store bought, glass rod stock for the stubs, with three seperate flat pieces for the bases, that he bagged up in his shop. First one of the flat pieces is glassed to the deck, then a pilot hole drilled through it and the deck, which helps to locate where to bond the second piece under the deck, which is also bored to size. Then the glass rod is inserted through the holes, plumbed , and bogged in place. when it cures, the bottom plate underneath is trimmed flush and the third plate is epoxied in place over the second. He lets the rod run wild, because the higher it is the easier it is to plumb, then trims it to length,. The stainless tube goes over the stub, and gets a bit of bog in the set screw hole to hold it down. He says that the ID of his tube was conveniently also 22mm for a nice fit. In the photos on his site, you can see that this assembly is clearly much stronger than the SS tube, which started bending at 75kg dead weight.

 

I like the glass rod stubs solution better than the molded in sockets as used by a few US west coast builders that i mentioned earlier. I would be happy to use ss stanchions and buy a couple of spares up front. They are going to bend at the top of the stub because they are thin walled, alluminum tube would be fine too and less likely to bend as you could use twice the wall thickness and still be a third lighter, i would have them anodised and install them with a non adhesive caulk. anodising is cheap and does a pretty good job of keeping corrosion at bay. I wouldnt use glass tubes.

Steve.

 

Oh yeah, up here in the north the guys with the Olsons (we have 5- 30s and 1- 40ft with the molded in sockets) remove the stanchions and put antifreeze in the sockets and plug them for the winter, this would not be neccesary with the stubs.

 

One of the problems with the molded in bases like on the Olson 30 is that the bases collect water. When I replaced mine, the bottoms of the stantions were all heavily pitted and rusted from the collected water. Buying titanium stantions was the first thing I did when I started working with Allied, and they are working great. Half the weight of the stainless, and no more pitting or crevice corrosion to worry about. And unlike glass and carbon they can be used in offshore races.