Stainless thickness

[claymore]

You can see from the title that I have the technical nouse of a stone gatepost. I had an electric anchor winch fitted last winter in deference to the ageing back and failing wind. I've been a bit over enthusiastic on the button a couple of times and have put a little dent in the gel-coat when the anchor came onto the bow-roller.
I've seen stainless panels fitted to the bow of a few boats so obviously this has been done before. There is a stainless steel stockholder near to where I live - What thickness of steel should I be asking for - assuming that it needs to be thick enough to do the job and thin enough to bend?

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Claymore
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[vyv_cox]

Anything over 18 SWG will be difficult to bend into a sharp right-angle unless you have specialist expertise/equipment. If you only need to bend it at a shallow angle and large radius you can go bigger. 18 SWG is 1.2 mm, which I think is the minimum for this application. I would prefer to use something like 3 or 4 mm, with the above provisos. Make sure that the grade is 316 and get the supplier to polish it, much easier than doing it yourself.

When you mount it you will presumably screw it to the boat. Suggest you get the supplier to drill the holes. Bed the plate on Sikaflex or something similar to exclude air from behind the plate, otherwise crevice corrosion will create unsightly red stains down the stem of the boat.

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[brianhumber]

No doubt some young turk will advise that modern glues are so good that one can match the profile of your fore stem with thin - say 0.5/1mm stainless plate and it will remain firmly attached with just the wonder glue.
For a person such as myself who got his practical spurs working on and on massively over engineered opposed piston diesel engines, Scotch and Foster Wheeler header boilers etc I would go for minimuim 2mm plate profiled as far as possible, fixed by welded studs through the stem onto internal doubler plate, all bedded and sealed with good adhesive sealant. This would not be ideal in a lightweight vessel due to trim considerations, which is why I put up with a few chips to make good every year on my pride and joy.

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[tony_brighton]

got the same problem - how much do they charge?

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[longjohnsilver]

Rugby world cup

Heard an interview with Kenny Logan this a.m. As the head in your photo is exactly the right shape for a rugby ball, has the Scots team requested your presence, just imagine the opponents surprise at seeing Claysies face peering up at them in a scrum. They'd all run away.

Scotland could be world beaters, all thanks to Claymore!! Book that plane ticket now, your country needs you!! /forums/images/icons/smile.gif

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[claymore]

Re: Rugby world cup

Its some time since a much younger Claymore strutted his stuff on a rugby field - we had leather balls then, and trained of Heavy and Bridies - nane ae this stuff they modern jessies are intae.
Anyway - my old parrot dropping encrusted little barnacle - how are you?


<hr width=100% size=1>regards
Claymore
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[richardandtracy]

I'm one of them youngish turks who thinks that you can go a fair bit thinner than 2mm.

If the plate is firmly seated all the way through against your grp with a fairly thin layer of sikaflex or something similar you should be OK down to about 0.5mm (24 or 26 swg). If over a largeish length, even stuff this thin won't be easy to bend. (I used to play with aircraft cargo bay floors, and 26 swg aluminium facing increased the life enormously - never got punctured even when only supported by a the 0.25mm thick glass skin of a honeycomb floor panel).

Make sure it's adequately attached around the edges (every 4 inches or so), otherwise you'd be better off going thicker.

Regards

Richard.


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[Avocet]

Am I right in thinking this is just for knock and chafe protection and doesn't take any "load" as such? If so, you might be able to dispense with the bolts and just "self-tapper" it into place - bedded on to a good layer of Sikkaflex as others have suggested to stop air going underneath. Just to add my vote to the thickness poll, I'd go for 2mm or even more. I'm sure the very thin stuff wouldn't get perforated but you'd possibly still dent it enough to crack the grp underneath.

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[richardandtracy]

Yep, this thin it's only good for surface damage reduction. If you really hammer it, then it will certainly allow the grp to crack, and worryingly it will hide the damage. However, if the gel coat's only been dented to date, surface damage reduction is probably all that's necessary.

Regards

Richard.


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[MainlySteam]

I'm all with Richard on this one. Some are suggesting using ss which is just about as thick as the mild steel deck of my boat (3mm on a 41 footer), and that is not easily dented.

I would suggest that 1mm thick at very most, bedded onto Sikaflex 291 (so you can get it off again) with no fastenings would kill the application. One will probably still need to get someone to bend it with a press to get the shape for a close fit unless you are not too fussed about its tidiness.

John

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[ParaHandy]

Chobham armour plating ...

dinnae pussy foot aroond, that'll do the job .... or inch thich SS. it'll work harden efter you've smacked the anchor into it a few times, if you pile oan the revs, and would have even cal-mac keeping out your way ............




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[tcm]

A stainless steel stockholder will probly want to sell in rather higher violumes than you want to buy. Also, it will cost you zillions of pounds in hacksaw blades, and then you'll hurt yourself drilling holes, or drop the drill into the sea and so on. Much better to waltz over to the other boats and askem how they got theirs made, and if they are total rubbish, or what.

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[vyv_cox]

My point in going for 3 mm was nothing to do with required strength. These plates are very visible, in a marina at least, and a bit of thin sheet steel looks tatty and is quite difficult to keep flat when screwed down, and therefore looking good. This was exactly how I made the one on my boat, which I removed two weeks ago because it looked lousy.

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[tcm]

right, so if even vyv's home-made plate looked lousy, i wionder what claymore's will look like?

I think they need to be thick to look good, and not denty. Which means they need to be made with proper metal bending gear, and polishy stuff. And then stuck on, er somehow.

Other alternative is to ignore the problem., After all, only the odd whack here and there, just fillitup?

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[claymore]

I agree with Vyv and don't want to spoil the ship etc (probably the first time I've ever used that expression appropriately) with something that is going to look cheap and tatty. I can through bolt it on as I've good access to the inside of the bow. I just bought a piece of 3mm aluminium from the stock holders for £15 - (24" X 14" - or whatever that is in metric) and they seem to have offcuts of stainless so I may not have to spend a fortune.

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Claymore
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[Evadne]

And once you've got the bow looking all shiny, I know just the accessory you need to finish it off. I saw one for the first time on a cat in Bembridge harbour the other week (sorry no pictures): a polished stainless steel Bruce anchor, with matching stainless steel anchor chain.

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[ParaHandy]

... all gleaming ... will complement his elegant attire, agreeably festooned with new-age jewellry (medallion etc), upon visting the Lord of the Isles and other places. perhaps he might purchase an offcut to fashion a pair of SS grundies the better to prevent anallic corrosion during the night and after a session on the "heavy and bridies" ...

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[MainlySteam]

If you use 2-3 mm ss it will have to be pressed into the exact shape you want because you will never pull it flush into final exact shape to the surface it is mounted on with screws/bolts of reasonable size. I am assuming your reference to bending means you want it to wrap around the stem in the common fashion (if you are only talking about a very narrow strip running vertically down the front face of the stem, then I am wasting my breath). Any screws/bolts will be redundant except for the point of view of stopping it falling off from its own weight.

Again, with thinner sheet, say 1mm, it will have to be pressed to the exact shape if you want it to look tidy, it will be a lot easier and cheaper to do though.

In both cases to get an exact fit one will probably need a 3D pattern for the shop to work from (which could be the boat, if handy). Again, all assuming you want it to wrap around the stem.

As TCM says, with ss it needs to be done by someone with the pressy, cutty, polishy things (and drilly ones too if you are going to screw it on) and experience needed to do a good job. In neither case is it necessary to screw/bolt it on, a sealant/adhesive such as Sikaflex 291 will hold it on (as an example we have a pressed into shape ss wear plate Sikaflexed to the cockpit coaming to protect it from the genoa furling line). While I am not normally attracted to gazing at anchor "ding plates", I cannot from casual recall remember ever seeing one screwed on.

If you want to spend a zillion dollars, the other option is to have one cast - Hinkley, for example, used to do a whole cast stem head fitting for some of their boats. Or, a rubber anchor?

John



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[claymore]

I have students.

Capable of reasoned debate. Quite good at research - taking responsibility for their own learning as we now say - which must be a let out for dedicated educators such as myself.
These students as I said are capable of reasoned debate but I have found that even with the most gifted of educators (me) and the most engaging of topics, there comes a point where their concentration just goes.
When I begin to read about Rubber Anchors and Stainless grundies, I recognise we are at that point.
I thank All of you for your contributions, I hadn't thought of a straight rectangular but - but as the anchor sometimes wags around a bit I thought I'd get a sort of V shaped plate fashioned to bend around that section of the bow. My already confessed to lack of technical ability - I never got beyond the Airfix Spitfire - means that I will get the yard to do it this winter BUT - thanks to your comments I will at least sound as if I know what I'm talking about!
Para - I understand that as I cannot make it this weekend - Jimi has decided to take his new Parrot along instead... my thoughts go with you at this difficult time!

<hr width=100% size=1>regards
Claymore
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