Making seacock hole smaller

[Roach1948]

OK, I have to admit that Roach had one, just one, of those ghastly new-style seacocks on her engine intake. Yup - I know, I know - but at long last I have got a brand-new Blakes to replace it.

So here is my dilemma: I remove the old 3/4 inch one (for the hose that is) only to find the hole in the hull is 1inch wide. The new Blakes is 3/4 inch - and the width of the fitting is that too. So my hole is too big. Seeing as a Blakes is held down with 4 bolts, I was wondering whether I will get away with packing out the hole. The flange on the inside of the hull is large, so I was thinking I might get away with that. Now if seems a bit lazy, I am not sure how to proceed if some woodwork is required; the hole is dead in the middle of a 3" plank -not that wide.

 

[Seanick]

Stick with the modern ball valve. Much more suitable for an engine intake, maintenance free, and cheap as chips. Easier to rod mud through as well!



Ok. Bore out the existing hole a smodge larger, so you have clean timber all round. Then make up a tight fitting plug, cut with a hole saw, and glue in. Using the center hole in the new plug use the correct size hole saw to cut a smaller hole. You should have a neat collar of timber left behind.Simples.

 

[burgundyben]

Ok. Bore out the existing hole a smodge larger, so you have clean timber all round. Then make up a tight fitting plug, cut with a hole saw, and glue in. Using the center hole in the new plug use the correct size hole saw to cut a smaller hole. You should have a neat collar of timber left behind.Simples.

I had some 'spare' skin fittings, in fact there is still one I need to attend to.

I used the method Nick describes, it works very well.

 

[Transcur]

Speaking from experience-see attached photo.

http://i201.photobucket.com/albums/aa201/willfinch36/STA78008.jpg

Be very wary of through hull fittings-this is after 8 years afloat -supposed to be bronze. Now replaced with a Blakes 3/4 intake with 4 bolts. The blakes fitting needed to be need packed out. Simple solution is to sleeve the 3/4 blakes fitting with a piece of old hose- no need to mess abour with unnecessary woodwork. Assuming you have a good pad in the inside.

Regarding ball valves- I saw one last week that fell apart just where the ball seating is crimped in. betwen the hex part and the ball-There was surprisingly a small amount of material there. It was fitted in very expensive yacht in Ipswich. It fell apart when droped on the ground.

What about this idea? Cast a skin fitting out of bronze with a grid on the outside,make the walll thickness 3 to 3.5mm(common) thick THEN cut a BSP thread 2.2mm deep- does'nt take much to work out the thickness left!!!!! I wont use one again.

Check them regularly.

 

[Seanick]

Speaking from experience-see attached photo.

http://i201.photobucket.com/albums/aa201/willfinch36/STA78008.jpg

Be very wary of through hull fittings-this is after 8 years afloat -supposed to be bronze. Now replaced with a Blakes 3/4 intake with 4 bolts. The blakes fitting needed to be need packed out. Simple solution is to sleeve the 3/4 blakes fitting with a piece of old hose- no need to mess abour with unnecessary woodwork. Assuming you have a good pad in the inside.

Regarding ball valves- I saw one last week that fell apart just where the ball seating is crimped in. betwen the hex part and the ball-There was surprisingly a small amount of material there. It was fitted in very expensive yacht in Ipswich. It fell apart when droped on the ground.

What about this idea? Cast a skin fitting out of bronze with a grid on the outside,make the walll thickness 3 to 3.5mm(common) thick THEN cut a BSP thread 2.2mm deep- does'nt take much to work out the thickness left!!!!! I wont use one again.

Check them regularly.

Sounds like a Tonval or brass skin fitting. Google Tonval and there is a test case where a boat sank after a year or so with a Tonval fitting.It was, if I remeber correctly, slightly overtightened, and quickly failed.
Most chandlers only stock these, but often refer to them as bronze. Likewise the ball valves that are chrome finished are usually brass too.
Proper bronze skin fittings and ball valves are available, they are not much more expensive, and I get them from Seaware in Penryn. Most chandlers mistakenly think Tonval is 'bronze', and okay for below w/l use.
You will find chromed brass ball valves on most 'most expensive' yachts!

Found the MIAB notes:
http://www.maib.gov.uk/cms_resources.cfm?file=/random harvest.pdf

 

[Tranona]

The most common material for seacocks (including Blakes) is DZR, although cheaper materials as described by Seanick are available. It is very clear which is which as DZR is nearly twice the price, but still not expensive, Bronze is available, for example from Vetus, but it is twice the price again as are stainless valves. DZR appears to be perfectly satisfactory.

 

[Roach1948]

So I learn...

what does DZR stand for?

 

[Tranona]

De-zincification Resistant.

Electrolytic reaction gets at the zinc in brass type alloys which are predominately copper. Hence the pink colour on failed fittings. The alloy of DZR as it name implies resists this process. Much cheaper than the even superior bronze alloy previously used by Blakes and seems to perform well.

Google DZR and you can spend a pleasant hour becoming a nerd on the subject! only if you are bored though.

 

[old_salt]

what does DZR stand for?

Acronym Definition
DZR Dezincification-Resistant (brass)
DZR Deutschen Zeppelin Reederei (German: German Zeppelin Shipping)
DZR Dan Zan Ryu (jujutsu)

This is a handy link:-http://acronyms.thefreedictionary.com/DZR

 

[KenMcCulloch]

De-zincification Resistant.

Electrolytic reaction gets at the zinc in brass type alloys which are predominately copper. Hence the pink colour on failed fittings. The alloy of DZR as it name implies resists this process. Much cheaper than the even superior bronze alloy previously used by Blakes and seems to perform well.

Google DZR and you can spend a pleasant hour becoming a nerd on the subject! only if you are bored though.

The ASAP-Supplies website has a useful page of information about the composition of the various brass and bronze alloys offered. I replaced a nasty old brass gate valve on the toilet inlet with a nice new DZR ball valve and bronze through-hull 2 years ago and it seems to be fine.

 

[Roach1948]

From Blakes

The body and plug are made of DZR1 (BSEN 1982 CC752C). A dezincification resistant brass for die casting
If zinc is leached from brass by sea water corrosion, the brass will become porous and fail. DZR1 resists the zinc removal and is approved by Lloyds if used in a marine environment.
The seacock bolts are manufactured from Phosphor bronze.