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Old 08-11-2018, 19:48   #31
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Re: Back to the dreaded bowsprit material construction considerations

I found this write up. It's the same boat and same bowsprit. Looks as if he put his anchors inboard. Are you guys saying put them on the end of the sprit?
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Old 08-11-2018, 19:50   #32
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Re: Back to the dreaded bowsprit material construction considerations

Bowsprit Replacement: s/v Gracie Emmet DE32 ę Downeaster Yachts.com
http://downeasteryachts.com/archives/1399
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Old 08-11-2018, 19:54   #33
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Re: Back to the dreaded bowsprit material construction considerations

You can passivate the welds yourself using chemicals or a dc power supply. I dont know the exact procedure but youtube does. Below is a series on building a stainless rudder and Keith explains passivating with a spray.

https://youtu.be/bBVnxhlB43Y

I think you are fine with hand buffing to an acceptable finish and then use the spray.

$1500 is a ton, i would pass on that.
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Old 08-11-2018, 20:41   #34
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Re: Back to the dreaded bowsprit material construction considerations

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Originally Posted by Eastward ho 24 View Post
I found this write up. It's the same boat and same bowsprit. Looks as if he put his anchors inboard. Are you guys saying put them on the end of the sprit?
Better clearnce for the bobstay when out at the end, but this practice exacerbates the "weight at the ends" issue. About the worst place on the boat for that!

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Old 09-11-2018, 04:34   #35
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Re: Back to the dreaded bowsprit material construction considerations

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I can't seem to find any one who will electropolish a piece that s 8ft long. I got one quote from a place in Chicago that said 1500. I was really hopeing to pay about800 or less. If I hand buff and polish does that make it passive as electro polishing would? Does any one know a place that would electropolishing on the east coast ( I'm in NJ de MD area)? This kind of puts me back at square one if electropolishing is gonna be that much it's gonna be like 1000 for the material and 1500 to polish.i might was well either a. Go carbon steel and paint it do the whole thing myself . I've got awlgrip laying around. Or b. ( I think is best all around)Just have a shop weld up the aluminium for me. But I'm still not sure what grade of alu to use, if I have to anodized it after, and what thickness of alu 4x4 I'd need to be on par with 4x4x.188 SS as far as strength. God I hate over thinking everything.
Boy, you sure are overthinking things...
Use 6061 T6 aluminum; 4" OD; 1/4" wall thickness. You could easily go thinner, but it seems like you're trying to build a tank. If you want to DIY, skip the welding (though that will be the most elegant), and bolt your fittings straight across. A little more ghetto, but it'll work.
If you try to anodize, you'll drive the cost back up. Just leave it plain.
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Old 09-11-2018, 12:11   #36
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Re: Back to the dreaded bowsprit material construction considerations

Looks like the aluminium is waaayyyyycheaper! And seems .25 thickness. Is about 1/2 the weight to! I wouldn't need to anodized? The eyes for all my stays would all be ss ( disimilar metals?)
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Old 09-11-2018, 12:48   #37
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Re: Back to the dreaded bowsprit material construction considerations

[QUOTE=Jim Cate; but this practice exacerbates the "weight at the ends" issue. About the worst place on the boat for that!


You hear that a lot, no doubt true for really bad conditions. However there is a Downeaster tied up next to me. It ain't no racing boat, an anchor at the end of it's bowsprit would do absolutely nothing. It's a stout looking boat.
I've had full sized people on the end of our bowsprit and could tell no difference in how boat sailed. If someone were to sail it across an ocean, I have a set of chocks on deck for the anchor with pad eyes. That's a lot of surface area just hanging out there.
It's part of having a bowsprit. Chain on bobstay is just not the way to go when you anchor a lot.
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Old 10-11-2018, 04:15   #38
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Re: Back to the dreaded bowsprit material construction considerations

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Looks like the aluminium is waaayyyyycheaper! And seems .25 thickness. Is about 1/2 the weight to! I wouldn't need to anodized? The eyes for all my stays would all be ss ( disimilar metals?)
Anodizing won't do much for dissimilar metals--you will still need to isolate the SS from the alloy with Tef-Gel or Duralac, and nylon washers where appropriate anyway. If you simply go with a brushed finish on the aluminum, you can always refresh it with a piece of sandpaper.

But to Jim's point about weight in the ends: you may not notice the weight of several people at the bowsprit end at the marina, but out in a steep chop the boat will hobby-horse a lot more than if the ends are light. This is huge for a heavy-displacement boat that tends to hobbyhorse by nature. For nearly any boat, you want to concentrate the weight in the middle as much as possible.

I deploy my anchor from a roller on the sprit, but always have a rope snubber coming from a hawsehole several feet back from the bow. Keeps the rode mostly off the bobstay. I can also lead the snubber through a fitting on the bobstay chainplate, which gives a better angle and guarantees no bobstay chafe.
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Old 12-11-2018, 19:54   #39
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Re: Back to the dreaded bowsprit material construction considerations

I believe 5086 aluminum is more corrosion resistant in seawater than 6061. Ask the experts at Pierce Aluminum Pierce Aluminum
They are one of, if not THE largest aluminum supplier to the marine industry.
I bought aluminum from them in the past and I remember them telling me that 5086 was the most widely used for boat hulls (aluminum yachts, aluminum Coast Guard cutters and Navy vessels). Also, 5086 is very weldable.

My wooden bowsprit was replaced about 18 years ago by a previous owner. It was done in 316 stainless steel with 1/4" wall thickness. It was fabricated in 2 parts. On the foredeck is a large stainless C-channel shaped structure fabricated with a mount for the windlass and side flanges for bolts that go through the deck and through internal beam structures below deck.
The second part is a roughly 9 foot long 4-1/2" OD 316 stainless pipe also with 1/4" wall thickness. It slides into the first component and is secured by a series of through-and-through bolts. The platform component consisting of the pulpit railings, anchor rollers, and SS gridwork for the teak boards is welded to the 9 foot pipe. It is very heavy duty and easily accomodates an 80 pound Spade-Usa primary anchor plus a 65 pound CQR secondary anchor. The rectangular portion on deck supports a Lighthouse 1501 windlass (also extremely heavy). The boat is a heavy displacement, cutter rigged, full keel double ender. The inner stay attaches to a fitting on the aft end of the rectangular component.
I recently dismantled everything for a total restoration of the boat and was happy to find no corrosion or stress cracks after 18 years of constant exposure to the marine environment including multiple extended ocean passages. There was only a small amount superficial staining that easily buffed out.
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Old 12-11-2018, 20:05   #40
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Re: Back to the dreaded bowsprit material construction considerations

I have a Gulf 32. Built my whole bow sprit of laminated teak and the support structure of 304, then built a whole new pulpit to fit. Then built the windlass support and roller system, I am new so donít know how to attach pictures. Perhaps someone can help me with that. Kim
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Old 12-11-2018, 23:34   #41
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Re: Back to the dreaded bowsprit material construction considerations

V child that's a pretty slick design. The round pipe slides into the box beam that's mounted to the deck. Pipes secured with through bolts if read correctly. Unfortunately I'm only 32 foot etube inside a tube would be over overkill for me.
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Old 12-11-2018, 23:36   #42
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Re: Back to the dreaded bowsprit material construction considerations

P.s are your Samson posts steel too?
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Old 13-11-2018, 04:24   #43
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Re: Back to the dreaded bowsprit material construction considerations

My understanding is 5086 is used as noted because of superior corrosion resistance in salt water. 6061 is used on decks and the rest of the hull because corrosion resistance is good enough and it is stronger.

Onlinemetals.com is a good place to find a primer in metals, comparison of grades, standard available sections, weights and prices.
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Old 13-11-2018, 18:19   #44
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Re: Back to the dreaded bowsprit material construction considerations

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My understanding is 5086 is used as noted because of superior corrosion resistance in salt water. 6061 is used on decks and the rest of the hull because corrosion resistance is good enough and it is stronger.

Onlinemetals.com is a good place to find a primer in metals, comparison of grades, standard available sections, weights and prices.

Gotcha! Makes sense. 6061 is a lot cheaper too.
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Old 13-11-2018, 18:32   #45
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Re: Back to the dreaded bowsprit material construction considerations

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P.s are your Samson posts steel too?

They are currently the original wood samson posts with a white epoxy coat. However, I am planning on fabricating new mirror polished stainless steel samson posts cut the same shape as the originals on my plasma cutter.
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