Thru Hull Materials

[Sailorman375]

Originally Posted by S/V Illusion

I wonder how many pages of comments it will take for the last person to recognize the answer is a matter of opinion.

Yes the opinion of most major offshore oil interest. Most of the middle east and others. Actually B-148 nickel aluminum bronze is preferred, but not available for recreational boats. There has been much research on this and I'll see if I can find the paper written by Ron Strang a noted engineer and considered an expert in the field. Now if you want to talk Super Duplex stainless and titanium you might have an argument.

[Sailorman375]

Here's a link to the article published in Valve World.

http://www.valve-world.net/pdf/vw100...ls_shipham.pdf

[CeesH]

Originally Posted by Stumble

The problem with the plastic ones is that to the best of my knowledge not a single one has been certified to ABYC H-27 standards. Which basically tests if they will snap if you accidentally step or pull on one. This isn't a rigorous test for most metal ones, but the plastic just snaps. Worse, the plastic snaps right where the pipe exits the fiberglass, which means there is no possibility of repair until the boat is hauled and a new one can be fitted.

The only way to prevent sinking is to have a plug large enough to plug not only the stand pipe of the thru-hull, but also the hole drilled into the fiberglass.

Just say "I don't like them" but please tell the facts..........

[zeehag]

marelon is a very excellent substance to use for thru hull fittings in a cal 28. yes, is opinion.
the ones placed in my islander 26 were supposed to last over 20 years--cannot get much better than that.
be careful in placing bronze fittings onto marelon thru hulls.
marelon is not going to corrode or suffer electrolyis. enjoy and have fun. these, as i was assured, are stronger than plastic.

[Freerider]

What do the big dogs use?

Morris, Hinckley, HR, Oyster, etc, etc, etc.........

[Sailorman375]

Only problem with marelon seems to be the need to cycle quite often to keep them from freezing. That and I think (and yes it's just my opinion) the stems in the ball valves are a bit of a weak link.

[Cheechako]

Originally Posted by Sailorman375

Only problem with marelon seems to be the need to cycle quite often to keep them from freezing. That and I think (and yes it's just my opinion) the stems in the ball valves are a bit of a weak link.

Yep. It's is super tough stuff... had to remove a couple before. (handle broke off) Marelon good... but not sure if the design is better now or not. I'm not a proponant of things that will go bad from just sitting. (ie: must be cycled often) How often do you want to crawl under your cockpit and try to cycle those hard turning marelon valves?
Boy it would be nice to see a comparison of the old ones and the latest... like a band sawed in half comparison to see if the shaft that cycles the ball has been made larger or etc.....
Saying these things are "a matter of opinion" is like saying The Chevy Vega (whose engines wore out at 35k miles) is not a bad product... it's just a matter of opinion....
Maybe the industrial valves above are a better design...?

[mikepmtl]

I am going through this right now. I am really leaning towards Marelon, but only if I have space for a true seacock. If not I will go bronze.

[Maine Sail]

Originally Posted by Stumble

The problem with the plastic ones is that to the best of my knowledge not a single one has been certified to ABYC H-27 standards. Which basically tests if they will snap if you accidentally step or pull on one. This isn't a rigorous test for most metal ones, but the plastic just snaps. Worse, the plastic snaps right where the pipe exits the fiberglass, which means there is no possibility of repair until the boat is hauled and a new one can be fitted.

The only way to prevent sinking is to have a plug large enough to plug not only the stand pipe of the thru-hull, but also the hole drilled into the fiberglass.

The Forespar OEM/93 series are ABYC H-27 complaint. They are quite robust.. I have pushed them 250+/- pounds pounds beyond the ABYC requirement in the smallest size..

3/4" OEM/93 Series

http://www.youtube.com/watch?v=-tzB3IiImpo

3/4" Marelon Ball Valve on 3/4" Marelon Thru-Hull Fitting

http://www.youtube.com/watch?v=l5ajZ3nfzzQ

There is a huge difference in strength between a valve on a thru-hull and a true flanged seacock..


Simply sticking a ball valve onto a thru-hull will not meet the standards in either bronze or marelon, in most sizes. Doing this with Marelon, ball valve on a thru-hull, it is about half as strong as bronze.

More testing here: Seacock Load Testing

[Maine Sail]

Originally Posted by Sailorman375

Bronze is a bit better in seawater service, but don't settle for something that just says bronze. Find out the ASME number like B-62. No one seems to want to state what the actual material is. Bronze can be quite a range of materials.

Most any USA avaible UL Marine / ABYC compliant seacocks are an 85-5-5-5 bronze. This includes Conbraco/Apollo, Groco, Spartan and Buck Algonquin...

[HopCar]

I probably shouldn't say this since I make my living selling marine hardware, but I don't think you need to change them. Maybe pull a couple for close inspection. You know what to look for.
If you decide to replace them I'd love the chance to quote you on them.

[Celestialsailor]

For myself...Marlon thru-hulls above the waterline and bronze thru-hulls below. Regarding valves...all bronze and I mean bronze. Not the yellow Chinese valves. I do not like the plastic valves. If you have to lay up your vessel for 6 months or more, they can be almost impossible to free up.
On a side note...I just moved my head sink drain above the waterline and used a Marlon 1" thru-hull. When I haul out, I will glass up the original thru-hull which was below the waterline.

[Boulter]

Originally Posted by Maine Sail

There is a huge difference in strength between a valve on a thru-hull and a true flanged seacock..

If I understand you correctly, a sea cock is a one piece through hull and valve, the other option is a through hull, with a valve threaded on. A true sea cock is to be preferred, especially one with a nice wide flange and three screws.

This is an area I need to address on my boat too. Thank you as a side effect of the conversation, clearing up this detail for me.

Boulter

[Stumble]

Originally Posted by CeesH

Just say "I don't like them" but please tell the facts..........

CeesH,

I gave the best information I had. If there are some that meet spec, then I don't have any problem with them.

Since there are aparently some that meet H-27 standards I would consider them reasonable alternatives. Particularly given thee weight savings of going marlon as compared to bronze.

[Saltyhog]

Originally Posted by Maine Sail

Most any USA avaible UL Marine / ABYC compliant seacocks are an 85-5-5-5 bronze. This includes Conbraco/Apollo, Groco, Spartan and Buck Algonquin...

Maine, I remember that you've written that before (about the 85-5-5-5 bronze), but I can't find anything on the Groco web site that confirms this. I want to believe it because my plan is to replace all existing (bronze thruhulls with stainless ball-valves threaded on - Previous owner , don't ask) with the Groco tri-flange adapters to bronze street elbows to bronze ball-valves. (I have height restrictions thus the street elbows.) Have you had confirmation from Groco regarding the composition? I also see that Groco has two lines of tri-flange sea-cocks. To your knowledge is there any difference in composition? The ball-valves look similar to the cheaper sea-cocks, so I'm again hoping for the 85-5-5-5 composition. I will say the chrome plated "red brass" ball concerns me a little.