Do I need a back plate to my new anchor rolling?

[UNCIVILIZED]

G10 is an epoxy/glass laminate that's formed under high pressure, so that the glass to resin ratio is quite high. Which, some flavors of the stuff are stronger than aluminum, but still are a good bit lighter for the same thickness. You can cut & shape it using woodworking tools, though it tends to be hard on cutting edges due to the glass content. But otherwise it's handy stuff, & has been a go to material in the racing community for many decades.

You can look up it's properties, along with many lists of suppliers on www.matweb.com & there are loads of threads here on CF about it, or where it's mentioned. Another good info source, & list of places to buy it can be found here on Sailing Anarchy Forums Good G10 source found - Fix It Anarchy - Sailing Anarchy Forums
And many folks buy it either from McMaster Carr, or Online Metals. It pays to shop around, as prices can vary quite a lot. Also if you can find a friend to split a sheet or half sheet with, it helps with pricing.

As stated by another poster, it's almost a given that the underside of your foredeck won't be flat. So it helps to do some planning prior to ordering materials, & especiallly before cutting them.

Which, making cardboard or doorskin templates to mock things up help a lot when doing such planning. And know that you can get thinner G-10 stock, like 1/8" & bond it together or stack pieces in order to get the thickness you need in specific areas. Plus you can glass over it, needs be, with any of the common reinforcing fabrics; axials, wovens, exotics... And of course you can reinforce any sections of the boat or deck that require it using them as well.

I tend to use epoxy mixed with chopped or milled (fiber) glass fibers to make structural bog (puttys or pastes), as it's quite strong. And there's plenty of info on such things on the WEST System & other epoxy websites. Along with good explanations of how to use it in the excellent (free) book The Geugeon Brothers, On Boat Construction at the WEST System site. Download it, along with all of their user guides. They're handy references, full of great information.

Also, if/when fiberglassing upside down (on the underside of the deck), wear a shower cap along with the other usual protective gear. And don't be shy about thickening resin a little bit so that it's easier to work with it from this angle.

BTW, aluminum works for the vast majority of the above (& other) applications too. It's cheap, strong, & easy to work with, again, using standard woodworking tools. Plus it may be a bit easier to source (find/buy) it at a good price.

Also, backing plates are only "too thick" when you have to repaint the waterline in that area due to the weight that they add to things
AKA Overkill Never Fails.


EDIT: With bow rollers & foredeck cleats the loads can be quite large (sometimes measured in tons), so you want to make sure that the deck is well connected to the hull in that area. As in some boats this joint can be fairly wimpy. And on some boats I've gone so far as to add additional glass to the hull to deck joint, & or added frames or ring frames connecting the two together. None of it's complicated, though there's a learning curve when it comes to technique. Nothing worth losing any sleep over though.

Also, another flavor (grade) of G-10 is FR4, & they're pretty much interchangable for these applications. But look up their physical properties to get the full scoop.

[Island Time O25]

Originally Posted by Cheechako

a) you will likely find you need some sort of wedge between the roller and the deck as the deck is most often not flat to the world.
b) make the biggest backing plate you can, but in that bow interior you may end up with THICK large fender washers on a couple of the bolts, depending on the room you have.
c) Dont be surprised if you have to drill another bolt hole to get enough attachment.
d) the underdeck may be lumpy You have to make shims to level things out under there for the backing plate.

We solved that issue with lots of thick epoxy sludge/putty and just before it set attached G-10 plate. Used ss bolts dabbed in vaseline to tighten and then took them out and installed the windlass and the cleats. Thinking back on it we definitely overbuilt but then again better err on the overbuilt side than the other way. To counterbalance the add'l weight of the plates and epoxy I took the second anchor off of the bow and decided against all chain for now.

Got G-10 on CL for almost peanuts as some guy had generous leftovers from some big job and was too happy to help out a fellow poor boat owner. Now if I can only find time to back all the rest of my cleats and hardware with G-10.

Personally, I find working with epoxy a much easier proposition then trying to figure out nuances of electrical installations, especially when they are interconnected and there are many possible permutations of sources and cross uses. ))

[captstu]

I don’t think we are solving real problem here. Tipper or roller should never see more load then the weight of the anchor, the deployed Shane, and a little bit of extra to tip the anchor out of whatever it’s the end.

The actual load of entry should always be carried by bridal that is securely attached to the boat and securely attached to the anchor rhode. Relying on the windless or cleat to directly to hold the chain is inviting disaster.

[raintoomuch]

Originally Posted by captstu

I don’t think we are solving real problem here. Tipper or roller should never see more load then the weight of the anchor, the deployed Shane, and a little bit of extra to tip the anchor out of whatever it’s the end.

The actual load of entry should always be carried by bridal that is securely attached to the boat and securely attached to the anchor rhode. Relying on the windless or cleat to directly to hold the chain is inviting disaster.

So, what are you proposing?

[UNCIVILIZED]

Originally Posted by captstu

I don’t think we are solving real problem here. Tipper or roller should never see more load then the weight of the anchor, the deployed Shane, and a little bit of extra to tip the anchor out of whatever it’s the end.

The actual load of entry should always be carried by bridal that is securely attached to the boat and securely attached to the anchor rhode. Relying on the windless or cleat to directly to hold the chain is inviting disaster.

There are plenty of times when anchored, or anchoring, that the roller sees enormous loads. Ones that make backing down on it using full reverse on the engine to firmly set it seem mild by comparison.

Think about what happens when the anchor is stuck, or set REALLY firmly. And you bring the boat overtop of it, so that the rode is straight up & down vertically. Thus you're using the full buoyancy of the boat, which is being pushed up & down by the waves, to (hopefully) break the anchor out. At which time the full load on the rode is on the roller, so that once the hook's freed, you can finish hauling it aboard.

In such circumstances it's not at all difficult to have loads well into the 3-4 digit range, even on a 30-something foot boat. Let alone if the anchor is truly stuck in such a situation. And all of these loads are bourne by the roller. Much as they are in a storm when anchored, if you don't have a snubber or bridle, the snubber breaks or slips off, etc.

Ever been anchored out when the conditions are so severe that the bow is fully submerging with each wave? As in several times a minute. Like it or not, regardless of how well you plan & prepare, sometimes the roller bears all of that load, well along with whatever the rode is cleated to. And the longer the lever arm (overhang) a roller has, the higher these forces will be.

And easy visual example of how much support rollers need can be seen on some of the Dashew's boats. Which despite having hugely stout rollers that are integral to the boat's aluminum hulls, there is also a piece of pipe that's welded both to the stem, & to the underside of the roller. It's purpose being to support the roller against the loads I've described.

The roller needs to be strong enough to take the full breaking strength of the rode, preferably with a good safety factor on top of this. Like a multiple of this (strain) figure: such as 2x, 4x etc. Since if the roller breaks at the same time that the rode parts, then how do you deploy your 2ndary anchor then? Without a roller? It's either that or wind up on the rocks, non?

Yes, much of the time a bridle or snubber takes most of the anchoring loads. Though in point of fact, it's not at all uncommon to lead a snubber over/through the anchor roller. However at times, the full load which is on the ground tackle is seen by the roller. That's a simple fact, period.