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Old 06-11-2018, 19:52   #1
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Back to the dreaded bowsprit material construction considerations

Just had a thread last week. I'm building a 316l ss bowsprit for my downEaster 32. I'm basically going off the westsail 32 square tube replacement as a guide. I figure the ws32 displaces 1000 more lbs and has a little more sail area. It uses a 4"4" square tube that's .120 thick (grade of SS not specified). I'm able to get 316l 4"x4" that's .188 thick so I assume if the ws32 is using 304 @.120 and I'm using 316l @.188(with less sail area and 100lbs less displacement) I should have the strength differences compensated for (?). During my research I've come across a few instances of people using carbon steel that's either epoxy painted or powder coated. I'm trying to figure if this option would have better longevity then the 316l ? It would be cheaper and stronger lb for lb. The asthetics of painted over polished ss are all the same to me. In my searches for electropolishing shops I've found a car place that does rims and such (probably doesn't know much about marine or metals), he suggested that a silver or chrome powder coat would make it last longer but I don't think he's right about that.i wouldn't think to powder coat or paint 316l however I would consider painting or powder coating carbon steel if that would make it a better choice over the 316l. And it's cheaper to powder coat then it is to electropolish so the carbon steel/powder coat would be cheaper. Price isn't the deciding factor I'm more concerned with doing it right then I am in saving a buck. I plan on doing extensive cruising in remote places. I'm sorry to beat a dead horse but I really want to sleep at night 1/2 way across the Atlantic.

P.s. my boat doesn't have a dolphin striker but I was thinking about adding one for more strength there isn't much of an angle on my bobstay. But if I'm plenty strong with out it then I'd rather not. Any experiences thought and opinions much appreciated!
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Old 06-11-2018, 20:14   #2
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Re: Back to the dreaded bowsprit material construction considerations

Paul Gartside builds all his own deck and mast hardware out of mild steel. He has it galvanized and then paints it.
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Old 06-11-2018, 20:22   #3
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Re: Back to the dreaded bowsprit material construction considerations

Out in left field and probably not appropriate for your overall design, but I am very happy with the box structure design of my bow spirit
The strength is incredible as is the security up front
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Old 06-11-2018, 21:01   #4
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Re: Back to the dreaded bowsprit material construction considerations

There are only very minor differences in the physical properties of 304 and 316 series stainless. The stiffness and tensile strength are essentially identical. The differences lie in corrosion resistance, and in your application, those differences too are minor. Pickling of welds is important for both alloys, and in general polishing does help both in appearance and in corrosion resistance.

Thus, using the heavier wall 316 will be more than adequate in view of your description of the application.

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Old 06-11-2018, 21:26   #5
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Re: Back to the dreaded bowsprit material construction considerations

Wow pelagic is one helluva nice boat! I'm jealous.

So do you think 304 vs 316l if they're both polished slot the same should I just use 304 (I can weld it with 309)
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Old 06-11-2018, 21:28   #6
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Re: Back to the dreaded bowsprit material construction considerations

Quote:
Originally Posted by Eastward ho 24 View Post
Wow pelagic is one helluva nice boat! I'm jealous.

So do you think 304 vs 316l if they're both polished slot the same should I just use 304 (I can weld it with 309)
The whole boat, hull and house, is Corten steel.
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Old 06-11-2018, 21:44   #7
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Re: Back to the dreaded bowsprit material construction considerations

Someday!!
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Old 07-11-2018, 09:50   #8
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Re: Back to the dreaded bowsprit material construction considerations

I had my 316l stainless bowsprit fittings and mast crane i welded electropolished by an outfit in Plymouth MA. I boxed everything and shipped it to them including bolts nuts etc.

They did a great job and shipped it back ready to install. Makes a big difference esp the welded areas.

I tig welded everything and smoothed the welds using flap wheel and pedestal buffer before sending.

I can't remember pricing but it was under $200 i think. Lots of smaller parts.

http://electropolishingsystems.com/
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Old 07-11-2018, 10:27   #9
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Re: Back to the dreaded bowsprit material construction considerations

Our bobstay rod failed in a place that was hard to inspect. We replaced it and all the pulpit steel w/316 stainless. The rod was polished but the steel under the teak was left rough. That was 20 years ago.

During that 20 years we sprayed the rough steel and parts hard to see with CRC Heavy Duty Corrosion wax. The steel shows no sign of corrosion although the wax does impart a light brown color. We also sprayed the lower "eye" and bobstay rod fork with the wax. Even though this is constantly wetted, there is no sign of corrosion and no sign that the wax coating is breached. We have probably replenished the wax coating 3-4 times in the last 20 years even though there is no sign it has worn away. We continue to polish the rod which always develops seasonal pits.
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Old 07-11-2018, 11:06   #10
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Re: Back to the dreaded bowsprit material construction considerations

I second Eastward_ho's comment. That's a beautiful saiboat, that Pelagic. Apart from the shape and the bowsprit, I loved the color scheme.

Someday...[sigh].
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Old 07-11-2018, 12:00   #11
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Re: Back to the dreaded bowsprit material construction considerations

Mild steel is fine, pipe can be used also. Pipe or tubing can be tappered to give the wooden spar appearance. Epoxy coating works well, powder coating is great.
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Old 07-11-2018, 12:07   #12
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Re: Back to the dreaded bowsprit material construction considerations

Great guys thanks!
Sailah did you send it to them in a mill finish to be polished?
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Old 07-11-2018, 15:11   #13
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Re: Back to the dreaded bowsprit material construction considerations

No I sent it to them after buffing with sandpaper and then a Scotchbrite deburring wheel mounted to my large pedestal buffer.

The mast crane I tried to get all the buffing done before welding since it would have been impossible once assembled
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Old 07-11-2018, 15:15   #14
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Re: Back to the dreaded bowsprit material construction considerations

Then they returned to me like this:

If it's going to be highly visible you really need to buff out any scratches since the electropolishing doesn't remove much material just basically "shines" it up.

After 2 seasons they basically look the same. I did get a little staining from bobstay pin but buffs right off.

Highly recommend electropolishing if you don't the welds will rust, even 316l
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Old 07-11-2018, 15:23   #15
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Re: Back to the dreaded bowsprit material construction considerations

Looks good rally good I'm in contact with the same place you went. Thanks. One more thing did you use 1/8 316 filler wire one pass?
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