Bronze or plastic skin fittings and seacocks?

[Trident]

When all is said and done…the idea of taking a perfectly good watertight hull…and then drilling holes all over is pretty stupid

It's scary how many boat builders make - in my own boat I filled 9 unnecessary holes in the hull when I bought it - I have three now - two toilet outlets for two toilets and a water maker inlet - this is on a 50 foot catamaran. I've just done 8 holes on a Leopard 40 for a friend and as he changes to freshwater toilets and dumps his air con (UK boat) he'll need 5 more filling ! Oh and there are 14 below the water line through hull lights to make the water glow blue on his boat too! Madness

 

[lustyd]

It's scary how many boat builders make

All depends on how you view the risk. Personally I think one through hull per job can be safer than a complex manifold which may well have a mixture of different metals and many, many more fittings that could fail.

 

[rogerthebodger]

All depends on how you view the risk. Personally I think one through hull per job can be safer than a complex manifold which may well have a mixture of different metals and many, many more fittings that could fail.

Yes, but I only have to close one sea cock to isolate the manifold and if one of the fittings leaks its easy to isolate and repair

https://flic.kr/p/WYNPGD

 

[lustyd]

Well we know how you view the risk. To me that looks overly complicated and wouldn't fit anywhere on my boat without losing a lot of storage space. Thankfully we're all free to chose our own route

 

[Trident]

All depends on how you view the risk. Personally I think one through hull per job can be safer than a complex manifold which may well have a mixture of different metals and many, many more fittings that could fail.

I agree, I more think that fewer holes are needed in general - on cats particularly many can be deleted and things like inside the hull depth on plastic boats make sense.

My friend who is an ex-Navy commander went to the extreme on her steel boat - the only hole in the hull is the engine water inlet. She has a composting toilet, all water outlets above the water line and piped to run through channels in the cockpit to drain over the stern. The bilge pumps do this also. I asked why the almost paranoid lengths to keep the hull integrity and she told me that in her youth she and 3 other girls had done a transat and had to take shifts for the last 4 days in to the UK hand pumping the bilge continuously to keep afloat - "still sore 30 years later" was her comment

 

[justanothersailboat]

+1 for TruDesign here. Yes glass-filled plastic composite is not as strong square-millimetre-for-square-millimetre as some metals. But they're pretty chunky and the collars make them very well supported and stable. They are specified to a strength that is abundantly high enough - if they were much stronger and you applied enough force to test that, you would just break something else instead, possibly the hull. I'm happier with the Trudesign collar arrangement than with a tall stack of gently corroding brass that all levers off just the thread of the thru-hull, which is what my boat came with in one place. Trudesigns fantastic IF they fit. Anywhere where designers assumed the old Blakes (which are great, but now super expensive) is so cramped that you have few choices. I raised the plinth of my heads to make room for the TruDesigns, big improvement in many ways.

Even TruDesign specify turning the valves on and off regularly to avoid them getting jammed though. They may be super low maintenance but neglect can kill anything on a boat, however good.

 

[Bouba]

It's scary how many boat builders make - in my own boat I filled 9 unnecessary holes in the hull when I bought it - I have three now - two toilet outlets for two toilets and a water maker inlet - this is on a 50 foot catamaran. I've just done 8 holes on a Leopard 40 for a friend and as he changes to freshwater toilets and dumps his air con (UK boat) he'll need 5 more filling ! Oh and there are 14 below the water line through hull lights to make the water glow blue on his boat too! Madness

Do you fibreglass the holes or cap them ?

 

[rogerthebodger]

One thing we do agree about is to have as few holes below the water line as possible how we do that is our choice

 

[lustyd]

I agree,

Not sure you read my post - you certainly weren't agreeing with what I said

 

[Trident]

Do you fibreglass the holes or cap them ?

Small ones are filled with milled glass and then several layers of fibreglass cloth inside across a wider area. Larger ones are ground out at a taper and filled with multiple layers of cloth in the usual way from smaller to larger pieces . I would never leave a fitting simply capped off

 

[Trident]

Not sure you read my post - you certainly weren't agreeing with what I said

I agree with one hole per job rather than complex manifolds

I prefer fewer "jobs"

 

[Tranona]

Lots of things. I’ve hit plenty of hard things in the sea. A few potential options: Floating wood, the backbone of a sleeping whale, a rock reef you don’t notice on the charts, a jet ski bike driven by a drunk etc. in every case I’d rather take that knock onto bronze than soft plastic.

BTW, DZR is weaker than bronze. Plastic, considerably weaker than both.

Given that the fittings are mostly within the boat, please explain how the whales etc are going to damage them? They would have to get through the GRP which is less strong than the metal. As I said you have a vivid imagination - not about the things that you might possibly hit, but the consequences.

 

[Zing]

“Yes our skin fittings (dome head/threaded, dome head/tail end, and recessed) from the ¾" size up to 2" all meet the IMCI requirement of a 155 kg static load applied to the end of the skin fitting thread. There have been no issues to date.

Our 1 ¼", 1 ½" and 2" size fittings also meet the stricter ABYC / UL1121 requirement of a 227 kg (500 lb) static load applied to an assembly of: skin fitting, ball valve, and tail where the load is applied at the end of the tail fitting (which is attached to the ball valve).

That's a different test from what we are talking about. That relates to protection from impact or stress on the thru-hull on the inside of the boat. It also does not compare the strength of bronze thru-hulls - they will be much stronger. I also think that meeting design requirements means little as they are often a low bar. For example the CE Category A Ocean category is a bit of a joke in my view and is no warranty of suitability for ocean sailing.

It is possible to make plastic parts as strong as bronze, but even a strong one like glass reinforced nylon such as TruDesign use will need a lot more material to achieve the same strength as bronze. A Google search reveals that glass filled nylon has typically a quarter to a tenth of the tensile strength of bronze depending on the alloy used. Not as tough either, by a long way.

 

[Trident]

That's a different test from what we are talking about. That relates to protection from impact or stress on the thru-hull on the inside of the boat. It also does not compare the strength of bronze. It will be much stronger. I also think that meeting design requirements means little as it is often a low bar. For example the CE Category A Ocean category is a bit of a joke in my view and is no warranty of suitability for ocean sailing.

It is possible to make plastic parts as strong as bronze, but even a strong one like glass reinforced nylon such as TruDesign use will need a lot more material to achieve the same strength as bronze. A Google search reveals that glass filed nylon has typically a quarter to a tenth of the tensile strength of bronze depending on the alloy used. Not as tough either, by a long way.

I know that - that was simply further information

The bit I actually replied to you about impact was this - which is what I put in my reply to you

" Our glass filled nylon 6 composite has very good impact resistance, much better than bronze or brass which is prone to cracking especially at lower temperatures or if electrolysis has occurred.”

 

[Zing]

I know that - that was simply further information

The bit I actually replied to you about impact was this - which is what I put in my reply to you

" Our glass filled nylon 6 composite has very good impact resistance, much better than bronze or brass which is prone to cracking especially at lower temperatures or if electrolysis has occurred.”

Weasel words from TruDesign. What about normal use and where the bronze is not damaged?

 

[Zing]

Given that the fittings are mostly within the boat, please explain how the whales etc are going to damage them? They would have to get through the GRP which is less strong than the metal. As I said you have a vivid imagination - not about the things that you might possibly hit, but the consequences.

No, I'm not hallucinating and am not deluded by confirmation bias unlike some I can think of. The thru-hull usually protrudes from the surface. It needs to be particulaly tough. Also we are not talking about whales damaging fittings, we are talking for example a whale's back bone bashing in a thru-hull from the outside.

As to risks aluded to before, often it is suggested that because risks are low we should forget them, but that reveals a misunderstanding of the significance of low probablility events. It is nearly always the low probability events that kill you and ignore them at your peril. What's more it's not even that low a risk and a quick search found this. From the insurer BoatUS:

"About 15 percent of the sinking claims in 2012 were the result of hitting something while underway".

 

[Fr J Hackett]

Do you fibreglass the holes or cap them ?

The key word was filled

 

[Tranona]

That's a different test from what we are talking about. That relates to protection from impact or stress on the thru-hull on the inside of the boat. It also does not compare the strength of bronze thru-hulls - they will be much stronger. I also think that meeting design requirements means little as they are often a low bar. For example the CE Category A Ocean category is a bit of a joke in my view and is no warranty of suitability for ocean sailing.

It is possible to make plastic parts as strong as bronze, but even a strong one like glass reinforced nylon such as TruDesign use will need a lot more material to achieve the same strength as bronze. A Google search reveals that glass filed nylon has typically a quarter to a tenth of the tensile strength of bronze depending on the alloy used. Not as tough either, by a long way.

Again can you explain the circumstances in which the relative "strength" of a through hull is relevant when it is mounted in a less strong material such as GRP.

You also seem to have little understanding of the purpose of the RCD and the underpinning standards.

 

[Tranona]

No, I'm not hallucinating and am not deluded by confirmation bias unlike some I can think of. The thru-hull usually protrudes from the surface. It needs to be particulaly tough. Also we are not talking about whales damaging fittings, we are talking for example a whale's back bone bashing in a thru-hull from the outside.

As to risks, a quick search found this. From the insurer BoatUS:

"About 15 percent of the sinking claims in 2012 were the result of hitting something while underway".

I do not doubt that sinkings are caused by hitting something while underway, but this does not mean that a through hull has been hit and caused the breach. As I said it is not the risk I was questioning just the consequences and nothing you say provides any evidence that such collisions cause a skin fitting to fail and sink the boat. Just your imagination.

 

[Zing]

Again can you explain the circumstances in which the relative "strength" of a through hull is relevant when it is mounted in a less strong material such as GRP.

You also seem to have little understanding of the purpose of the RCD and the underpinning standards.

Is it less strong? Not usually. My thru-hulls go into thick solid composite, which will be stronger than the thin webs of the outside of the mushroom of the thru-hull - only 2mm or 3mm thick typically. Aren't yours built that way? Even if it went into a sandwich I think you'd find that the penetration area was strengthened very considerably.

So please say why the RCD is not applicable in the way I implied.

As to skin fitting collisions needing evidence of their capability to sink a boat, sorry, I don't have all insurance claims or accident records to hand, maybe you do for you to suggest it is not even a risk? It completely obvious that skin fitting failure can sink a boat. Really your argumentation on this is not credible!