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Old 25-06-2010, 00:25   #226
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Originally Posted by GordMay View Post
Can't any metal boat be repaired (at least temporarily) with Fibreglass (patching) materials & techniques?
If my memory is correct Moitessier did repair his boat with pop rivet.
For aluminum strength if only we could only ask Alain Colas.
In welding any and every weld is a challenge. There are the virtuosos who produce perfect welds but they are rare. There are the hard workers who always strive to produce a better weld and there are the one who find welding easy and mostly produce rubbish.
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Old 25-06-2010, 08:54   #227
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From Aluminum Strength vs Steel Strength

"An aluminum hull structure, built to the same standards, weighs roughly 35% to 45% less than the same hull in steel. As a result, if high strength is of the highest priority, the alloy boat can be built to the same structural weight as the steel vessel, and then be considerably stronger.

This is less of an issue for larger vessels which are able to carry the necessary displacement for whatever materials choice is made. For smaller vessels however, the weight of the hull structure is very much an issue. For a small cruising vessel, say under around 35 feet or so, steel becomes less optimum, as one must resort to a large water plane and a large displacement to carry the weight of the structure.

When alloy is designed to the same standards as steel (ABS, Lloyds or other similar classification society), it is made to be higher in overall strength. The reason for this is that aluminum reaches its "endurance limit" sooner than steel in terms of flexure. Therefore the rigidity of structure (deflection) becomes the limiting design criteria for an aluminum structure, and this forces a higher than necessary overall yield and tensile strength.

With steel, one designs to the yield point of the material instead, since for steel, flexure and rigidity are not ordinarily a limiting issue. For steel therefore, the yield point of an "equivalent" structure will be considerably less, as we will see.

One advantage of steel is that between the yield point of mild steel (around 36,000 psi) and the ultimate tensile failure point (around 60,000 psi) there is quite a large plastic range (around 24,000 psi or roughly 40% of the ultimate strength), permitting a steel vessel to endure deflection without failure, so permitting considerable ability to absorb energy."
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Old 25-06-2010, 13:25   #228
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Nice quote, your point?

Thomas
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Old 25-06-2010, 13:30   #229
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Welding up your own copy of an anchor or welding up your own design is probably one of the most dangerous things you can do for your boat. Your boat/home is hanging on that piece of welded together metal and if you did not do the perfect job or missed something in the design from the original - then your boat, maybe with you and your family or without may just break loose and end up on the beach/rocks/reef/ or floating over the horizon to points unknown.
- - Some equipment is just so basic to safety that trying to "save" a few bucks may just cost you the price of your boat and maybe much more. I would suggest instead making anchor chocks for your bow to store your purchased, proven quality anchor.
Oh well then maybe I should just leave everything to the professionals then cause they've got my back right? I'm sure everything that is professionally designed and manufactured by expert fabricators will preform perfectly with no flaws? There is no way that in something as most basic to safety as an anchor that I (the uneducated non professional) would be able to do the job nearly as well as the experts cause they know all the tricks. And I'm sure that if my store bought CQR anchor drags and my boat ends up on the beach the Geoffrey Taylor will be out there helping me kedge the boat back into the drink, apologizing profusely and offering a full refund and paying for any damages due to his failed design.

Comments like that are what keep people trapped, laying down bill after bill for something that could be done themselves. I for one like to take some responsibility for the safety of my boat. There is no reason why one couldn't build an anchor as well as any "professional" fabricator the information on how to join two pieces of metal together is out there, a trip to the library and you could have at your disposal the wealth of information that these same "professionals" have studied, it's not rocket science, it's anchors. Doing it yourself enables you to make sure it's overbuilt and isn't going to fail on you, let's you make sure there are no corners cut and things are well built, when you buy something mass produced it's been widdled down to fit a good costrofit ratio and usually the quality and life of the product fall somewhere near the middle of that equation with profit rising high above everything else. So really is making your own anchor the most dangerous thing you can do on your boat? Well that depends I guess, you can either rely on your own welding or you can rely on the welding of some other person, someone whom you have no idea who they are, how much training they have (if any), how much they got paid/care about the quality of their work. Chances are any anchor you buy is (unless cast) welded up by some poor third world worker paid a dollar a day or less, is that more dangerous than trusting something that you tried your best to do well? C'mon it's anchors, do you weld osirissail? do you really think it's that hard to get your 50 000- 70 000 pounds per square inch of weld into mild steel? if so lay down a few extra welds and you should be laughing. As for a working design... copy one that works it's not hard just make a couple of cardboard patterns and measure the angles between the flukes and presto: Anchor.
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Old 25-06-2010, 14:48   #230
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Yachts66 whats yours?
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Old 25-06-2010, 16:09   #231
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DIY Anchor...

I also see no reason why a competent boilermaker cannot put together a functional anchor.

My caveats:-
* A DIY anchor would almost certainly need to be heavier and ,larger than a commercial product to have the same effectiveness.
* That nice finish that lasts so well is going to be hard to do.
* In common with most DIY boat projects it's going to cost more and take longer than parting with the cash.
* It's very possible that the first attempt won't work all that well. Continued modification and testing is likely to be the norm.

The big upside is that after the anchor is made to the designer/constructors satisfaction they will know more than they really want to about attaching their boat to the bottom of the sea.
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Old 25-06-2010, 17:14   #232
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Boracay - you got that right!. I'm going to put wheels on the ends of my anchor so I can roll it around a bit on the bottom till I find a nice spot to dig in...or roll it up the side of my boat when I'm done.

Actually, maybe this would be a good project for my TIG class...then I can ship it to one of you to stress test it for me.
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Old 25-06-2010, 17:37   #233
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The little monkey said:

Quote:
Yachts66 whats yours?
To which I respond: It was your post and your quote, I was just trying to figure out the point you were endeavoring to make with it is all.

Boracay: I think you hit on the primary point even if you did so inadvertently. Sure you can weld up your own anchor, and if you're a good welder you can probably do it as well as a anchor manufacturer. Sure the cost of materials would be less than the cost of buying a ready made anchor, but when you add your time, the time it would take to test your copy to be sure it worked like you wanted it to; when you factor all that in, I suspect you're better off buying the Manson or Rocna off the shelf. They both give discounts if you ask I think.

As for the best coating, my money would be on hot dip galvanizing for a steel anchor. The little monkey probably doesn't like that because I said it, but I still stand by it. Hard to beat hot dip galvanizing for a steel anchor, unless it's made of stainless of course, but that approach brings with it a whole different set of issues, not to mention the cost.

Monkey: You put wheels on your anchor all you want. I'll just use my windlass. To each his own I guess.

Regards,

Thomas
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Old 25-06-2010, 18:14   #234
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SaltyMonkey prefers all stainless steel from the scrap yard than galvanized dodo dip, and he thinks you people are way too concerned over the weld quality which is really subjective anyway. If it looks good and you can see some penetration that's about all anyone can ask for. The weld will outlast the metal anyway even if you don't make a theoretical 70k lbs fit. And work and time? Come on, this is nothing. I could get three done in an afternoon and still have time for tea and singsong fun with Lady Marmaladia.

I'm going to put an electric motor on mine and spray paint "Yacht66" on it and call it a Roberts 65.
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Old 25-06-2010, 20:01   #235
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... and he thinks you people are way too concerned over the weld quality which is really subjective anyway. If it looks good and you can see some penetration that's about all anyone can ask for. The weld will outlast the metal anyway even if you don't make a theoretical 70k lbs fit.
With all of that experience of metallurgy & welding behind you, who couldn't agree?

Weld quality subjective? Who fed you that line of b.s.? B.S.? If you can't lay in a weld & know that it is good, you shouldn't be welding!

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Old 25-06-2010, 20:16   #236
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Don't bitch to me Bangkaboat~!

I'll be sure to tell my instructor who has 30 years PGE and their senior instruction, is an American Welding Society (AWS) Certified Welding Inspector, Certified Welding Educator, and is certified in all positions in the MIG and Arc welding. And who has highlighted for me very strongly that a weld can look absolutely great on the outside, but no one can tell just looking at it - not even the best. The only way you can really tell is by xray or $onigraph - which very few do.
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Old 25-06-2010, 20:18   #237
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There are plenty of anchor designs that work well out there so testing shouldn't be a problem. A tape measure and a few angles copied onto cardboard should do it. There are also bona fida designs that you can purchase. I have one now and intend on making two for my boat primarily because they aren't available comercially. However, SaltyM...I don't think stainless is a good idea. It doesn't do well without oxygen (in case you want to hole up for hurricane season somewhere or something) and many alloys are not that strong at the weld even with the correct rod (which will be very hard to determine if you have no idea what the parent alloy is from the scrap yard). Stick with the lowest carbon mild steel you can find Less carbon = less rust) and the most robust anchor design. Sending it out to be hot dipped is an option but you might want to wait until you are in Mexico or someplace more reasonable, you know, one of those countries you spoke of where people are paid a buck a day. If you choose a design that is robust a little rust won't be a big factor and paint will do. The robustest anchors are the ones that weigh alot but they hold the best also. Nothing like a pair of yachtsmans if you have the ability to handle them. But, of course, you can weld up your catheads and fabricate a simple lever/ratchet windlass so that won't be a problem.. (I'm doing the catheads but I think I just found a second SL 555 for the right price so I won't have to build the windlass after all)
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Old 25-06-2010, 20:24   #238
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Don't bitch to me Bangkaboat~!

I'll be sure to tell my instructor who has 30 years PGE and their senior instruction, is an American Welding Society (AWS) Certified Welding Inspector, Certified Welding Educator, and is certified in all positions in the MIG and Arc welding. And who has highlighted for me very strongly that a weld can look absolutely great on the outside, but no one can tell just looking at it - not even the best. The only way you can really tell is by xray or $onigraph - which very few do.
With some experience you will be able to tell very accurately when you make the weld. That's what counts and because you made it, you know.
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Old 25-06-2010, 20:40   #239
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With some experience you will be able to tell very accurately when you make the weld. That's what counts and because you made it, you know.
Pah! Ptui* If it looks good to me its good enuf. I'll be TIGging while you are still playing with your stick.

Go with stainless. The salinity is stronger in the mids and your galvanized doodoo dip won't hold up.
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Old 25-06-2010, 20:41   #240
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...Sending it out to be hot dipped is an option but you might want to wait until you are in Mexico or someplace more reasonable, you know, one of those countries you spoke of where people are paid a buck a day...
That wasn't me...that was the other guy sayin that
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