Material for Windlass Backing Plate ?

[delmarrey]

I have a balsa core, which can crush if there is not enough support. So I epoxied one 1/8" sheet on top and faired in the edges for epoxy filler. And then glassed over that.

On the inside I laid in 4 sheets of 1/8", sucking them up with a T-bar on top while all were still wet, then let it all cure.

Afterwords sanded it flush on top and cut the holes. And then filling the core where ever possible.

(no comments on the light wiring please-that's been changed too)

[Bergovoy]

i used a product called 'starboard'.. it is just like those plastic cutting boards... I was told they use it for cabinetry on boats... It comes in different thickness.

I would think thta stuff would be perfect for backing materials, and could be glassed in, it hace have recessed threads and glassed in..

but, not totally sure... anyone else heard of starboard??

[North26West80]

Starboard is great stuff for a few things, especially outside because its very UV resistant. But it is a bit soft and will deform easily and more so if hot. I use it for companionway hatch boards, stern-rail seats, etc. Almost nothing will adhere to it, so forget about fiber glassing it.

[North26West80]

If you want to preload the bolts, instead of wood, I'd use silicon sealer under the backing plate and then wait for it to cure before final tightening. I don't know why this is necessary though. Locktite works too.

My favorite backing plate material is leftover pieces of fiberglass when I cut a hole for a locker door or something. For something pulling in sheer I'd epoxy it in place with West System. For a quick job that is pulling perpendicular to the backing plate I've been using West Marine Structural Body Filler, which is cheapo (probably Bondo) resin with fiberglass strands. It fills the irregularities and transfers the load and it cures in five minutes and it is cheap. (Also works well with metal backing plates.)

[Mark Johnson]

Delmarrey,

REALLY BEAUTIFUL WORK! Looks like you've: "been there, done that".

I just looked up G-10! I have done so much boat work, the way I've always done it, that I was unaware of this material. For applications where it might be hard to get, too expensive, or too what ever...

I have always made my own fiberglass/epoxy sheet. Then I can cut all sorts of pieces out of it. In this photo, I needed a 1' X 8' X 3/8" thick "worm shoe" for the bottom of my Tri's minikeel. (An application where 10,000 pounds would sit on it) To make the sheet, I just get two wide "perfect" planks. The bottom one is suspended above my work table with a few crosswise 2X2s, then covered with thin sheet polyethelyne. Then I cut perhaps 15 or 20 pieces of my chosen glass fabric, mat, or woven roving... a bit larger than the plank.

I lay down a piece of fabric, and wet it out quickly, by just pouring the resin on the fabric, and rolling, or squeege it out VERY quickly. Then piece No.2 the same way, then the third piece, etc. My lay up was almost 5/8" thick, to be eventually squeezed down to 3/8" thick.

You can make it resin rich, and it goes REALLY fast! I use med. hardner, and can lay up all 20 pieces of glass in about 15 minutes!

Then I cover the glass layup with another piece of thin polyethelyne sheet, and cover with the TOP plank. (BOTH PLANKS MUST BE VERY FLAT WITH NO BENDS OR TWISTS)

Now I use large "C clamps" every 8" or so, all the way around, and tighten them in opposing pairs, (like I was torqeing down the head of an engine) Just snug them up first, then one more turn all the way around, then another round, repeat untill about 10 minutes of this, and you can't get them much tighter. NOW you have squeezed out perhaps 60% of the epoxy, and it is incredibly resin lean, like we want it.

The entire process takes about 45 minutes! Four or five hours later, remove the boards, peel off the polyethelyne sheets, and you have a damn near perfect fiberglass sheet.

Another alternative... I have used sheet phonolic, AKA "Micarta", for such applications. It glues well, holds up to the UVs indefinetly, WITHOUT paint, although it does take paint well... and is even more crush proof than sheet fiberglass. This is the stuff that they used to make the cheeks for "blocks" out of.

Keep up the good work, Mark

[GordMay]

Originally Posted by Bergovoy

i used a product called 'starboard'.. it is just like those plastic cutting boards...

King “StarBoard” is not intended to be a structural material, and requires structural support every 16-18 inches (typical spacing for 3/4”).

From their FAQs*:
"... Is King StarBoard as strong as marine plywood?
There are many types of marine plywood. The better ones are stronger than King StarBoard, which was not designed to be a structural material ...”

*Here ➥ 24/7 Info Center - King Plastic Corp.

See also ➥ http://www.kingplastic.com/CMS/Media...gStarBoard.pdf

Yours (post #8) sounds like a good installation, to me, Weyalan.

See also:
“Design Loads for Deck Hardware”
Here ➥ Design Loads for Deck Hardware - ABYC Section H-40, table 1 Cruisers & Sailing Photo Gallery

[Mark Johnson]

I used bits and pieces of Starboard all over our boat, It is GREAT stuff, but being really heavy, large fabrications with it would be a no no on a trimaran like ours. It doesn't take glue or caulk at all. (will not bond) I do however, use 5200 UV to bed it down or connect two pieces, just to keep salt water out of the gaps.

It machines well & routs well, but if you sand out your cut swirls with 80 grit, you then need to sand what you sanded, with at LEAST 220 grit. Otherwise, the sanded roughness will get REALLY dirty, on an otherwise stark white piece. So far, nothing I have tried, Chlorox, soaps, solvents, will clean it back up. Either don't sand your routs & cuts, or sand them really well with finer grits to remove the fuzzyness.

The stuff doesn't tend to split, and takes fastenings (self tapping screws) REALLY well. WAY better than wood.

The dinghy cradle below, had the verticle piece attached to the horizintal base, with 2" long #10 screws, every 1.5"!

The stuff is good for hand rails, toe rails, solar supports, bases under lightly loaded pieces, etc. NOT STRUCTURAL APPLICATIONS!

It will easilly take a mild bend, but to make even a SHARP radius... You can heat a strip of say, 3/4" 1 X 2 toe rail, almost to the melting point, (with a heat gun, back & forth), and bend it in an arc to match the tight curve you need, just over bend by 10%. Let it cool for 15 minutes this way, and it will stay indefinetly.

It is NOT appropriate as a backing plate for anything that has enough load to need one. It could compress over time.

MY Starboard is mostly 15 years old, and NO sign of UV chalking or damage yet.

Mark

[Bergovoy]

i wouldnt suggest starboard for structural element by itself, but for backing or blocking material, I am not sure there is much a difference then a pioece of sheet metal... that was sandwiched...

i was just thinking of blocking and beefing up of the material to be able to spread the load out over a lrger area...

basically looking for 'compression' strength not sheer... but yea, i will defer to you all... no worries...

[sailing_gal]

I am in Spain, about to install a Lofrans Falkon on my Island Packet 420. I am looking into backing material. In Spain, they have never heard of starboard, and if it won't take epoxy, I am not interested. However, at the local chandlery they have something that is a plastic material here that they call Plastico de Medida that comes in 80mm sheets, cut to order. I am thinking it would be easier to work with than stainless or aluminum (and right now, easier to get). but I am unfamiliar with the product. It looks something like starboard, but is smooth. I was told it was also used for plastic windshield on yachts. Anyone familiar?

[John_Trusty]

Talk about revisiting an old thread ... Anyhow sailing_gal (and apology in advance if you know this already) all 'medida' means is measured, meaning they sell it measured sheets. King Starboard is just the brand name of High-density polyethylene (King StarBoard® | King Plastic Corporation) which is as described in this thread not the best material for backing for a few reasons - it will not glue with anything (epoxy, 3M 4200, etc.) and has minimal structural strength. It's a good filler if you don't compress too much, and is UV resistant. Similar to soft plywood that will not rot. Here are some good descriptions from a Spanish plastics vendor with English translations available -- https://www.plasticosferplast.com/es.html

Best backing material should be G10 pre-made laminated fibreglass, which is an international standard product. You don't need the FR4 (fire retardant stuff) for backing plates. You may need to double-up a couple sheets and make a laminate, depending on the thickness you can buy locally.

[sailing_gal]

Thanks, John.

Do you think I would find the G10 at a local home improvement store? (A Spanish version of a Lowe's)?

Although the starboard stuff would like nice for the pad under the windlass, cause I could make it match my boat- but if it won't take epoxy, I won't be able to get a good seal on the curve of my deck. Back to SS 316 for that I am thinking. I don't really want to mess with wood.

[Stumble]

Originally Posted by sailing_gal

Thanks, John.

Do you think I would find the G10 at a local home improvement store? (A Spanish version of a Lowe's)?

Although the starboard stuff would like nice for the pad under the windlass, cause I could make it match my boat- but if it won't take epoxy, I won't be able to get a good seal on the curve of my deck. Back to SS 316 for that I am thinking. I don't really want to mess with wood.

You might be able to find G10 there, but I doubt it. But if you are in a big city you might be able to find it at a commercial plastic supply shop. It's a pretty common industrial material. You may also be able to find a machine shop supply house with it.

[Tiemo]

I'll see if I can revive this thread instead of starting another one. I looked at an Able 34 today that the owner says has a solid fiberglass deck, but we cannot see it because of screwed on teak over the entire deck bow to stern and a teak headliner and paneling throughout the entire cabin.

I have the typical concerns regarding the "2000 screws in fiberglass" fear that seems to draw so many discussions on many sailing forums. When I view the so called "sold fiberglass" deck from below via the chain locker I could clearly see ~1.25" - 1.5" deep and ~1.5" diameter holes drilled through plywood mostly for the windlass switches. Finally, my question:

Is it likely that the builder put plywood only at the deck area of the windlass so as to create a structurally sound mounting area? Or, would seeing plywood there insinuate that the remainder of deck areas are most likely constructed of plywood sandwiched between fiberglass and teak over the top.

The teak is on it's last legs. The boat was built in 1988 and most all the filler between the actual teak is higher than the teak itself. I am concerned that perhaps the owner, that has owned the boat for 4 years does not have a clue how the decks were built, or just wants me to assume he is right and therefore believe the decks are not subject to the pitfalls of decades of possible water intrusion into plywood.

Even after his "filling" of the gaps with acetone thinned urethane there are still many pockets where water could have seeped in for years prior to his attempted remedy of sealing it all.

I've read time and time again of surveyors declaring acceptable moisture readings only for new boat owners to find significant problems soon after.

Thanks for your advice.

[Island Time O25]

Under the scenarios you describe if the boat is otherwise sound if a buyer I would come up with an offer that assumes the teak deck is a goner and will have to be worked on.

If a seller I would provide some proof of a solid deck, up to drilling the holes, etc but only AFTER a valid accepted offer made subject to the usual blah-blah.

[Tiemo]

Thanks Island Time. I'll pose your seller version to him - accepted offer and then show me the beef (solid fiberglass). What I fear more than the dozens of hours of teak removal and fixing holes / painting etc... is the possible necessary demolition and replacement of portions of the deck. The seller told me to hire a couple of local guys (it's in Mex) to rip it off for $200 or $300 if I don't want teak; which I don't, but I also don't want unskilled labor going to town with crowbars fueled by Tecates, Tequila and Coronas. The blah-blah is what I've got to figure out as well. This is a FSBO. I suppose I can clone a standard purchase contract from the internet and then hire a U.S. based Maritime Document company to handle the rest. Seller's already told me he thinks surveys and document co's are BS and to save my money. I'd rather spend it and sleep at night.