Trudesign skin fitting size

[Marceline]

Hi - just hoped to check -

We're changing a hand basin waste water pipe skin fitting to a trudesign seacock and bit unsure of the size we should order

We'd measured it with calipers and its about 31.35mm for the diameter of the outlet skin fitting (about 1.25 inch) ,



but think we took the wrong reading the sizes for the tru design fittings (should it have been the diameter size inside ?)





they offer fittings sizes of 1", 1 1/4", 1 1/2" - guessing it should be the 1 1/4" we should order, but just wanted to ask if making big mistakes etc

TruDesign Composite Domed Skin Fitting - Force 4 Chandlery

thanks for any help/pointers

 

[Marceline]

ps - as a backup plan - if we can't get this skin fitting off would adding extra sealant around it be ok (the skin fitting seems a bit loose) or even sealing it up if we can't get the skin fitting off ?

 

[coopec]

So, 1.25 inches = 1.25 × 25.4 = 31.75 millimeters.

Your measurement is 31.35 which makes the difference .4mm which is so small it can be ignored.

 

[LittleSister]

Such fittings (whatever manufacturer or material) are sized for the bore - internal diameter - of the pipe (in your case basin waste pipe) they are to fit to.

Trudesign and similar fittings will have a larger external diameter (as a result of the thickness of material required for strength) for any given internal diameter (thus requiring a larger hole in the hull than metal fittings and cheap plastic fittings like you currently have). Those cheap plastic fittings are only suitable for use above the waterline.

(I have a vague recollection that the actual internal diameter of Trudesign fittings is slightly less than the notional size, too, in order to provide the thickness of material required for strength of the hose barb to which the pipe is fitted, but this can be ignored - go by the stated notional size).

So you need to measure the internal diameter of the drain pipe you want to fit to your new skin fitting (which will probably be determined by the size of the basin drain pipe fitting ) to establish which size through hull-you need. Then you will need to enlarge the current hole in the hull to accommodate the external diameter of the new fitting.

You may or may not find online drawings to tell you what the external diameter (dictating hull hole size required) will be for each Trudesign notional internal size.

 

[stranded]

Such fittings (whatever manufacturer or material) are sized for the bore - internal diameter - of the pipe (in your case basin waste pipe) they are to fit to.

Trudesign and similar fittings will have a larger external diameter (as a result of the thickness of material required for strength) for any given internal diameter (thus requiring a larger hole in the hull than metal fittings and cheap plastic fittings like you currently have). Those cheap plastic fittings are only suitable for use above the waterline.

(I have a vague recollection that the actual internal diameter of Trudesign fittings is slightly less than the notional size, too, in order to provide the thickness of material required for strength of the hose barb to which the pipe is fitted, but this can be ignored - go by the stated notional size).

So you need to measure the internal diameter of the drain pipe you want to fit to your new skin fitting (which will probably be determined by the size of the basin drain pipe fitting ) to establish which size through hull-you need. Then you will need to enlarge the current hole in the hull to accommodate the external diameter of the new fitting.

You may or may not find online drawings to tell you what the external diameter (dictating hull hole size required) will be for each Trudesign notional internal size.

I believe Trudesign use the same size through hull hole as eg DZR equivalents, so should be no need to enlarge holes if replacing those. No idea about the OP’s plastic fitting though.

 

[andsarkit]

TruDesign Domed Skin Fitting - 6 Sizes

 

[john_morris_uk]

If the current plastic fitting is loose, I’d definitely be removing it. Trying to reseal it in situ is never going to be satisfactory.

 

[geem]

You dont seem to have a seacock fitted? Will,the wash hand basin not flood when you lean over?

 

[Boathook]

@The normal way of sorting a new fitting is the existing hole size through the hull so measure the thread and then match up with the tru design fitting.

 

[Copious]

Try DSLittle on this forum. He has just (this week) fitted 7 of them!

 

[Tranona]

Yes, you are measuring the wrong part. That looks like a 13mm (1/2") hose which is common for a sink waste, but maybe 3/4". As it is just above the waterline it should really have a ball valve (seacock) on it. Suggest you take it out and measure the inside bore of the hose and buy a DZR ball valve with a hose tail of that diameter and a matching skin fitting. You can of course use TruDesign but it is really not necessary as either will last indefinitely and DZR is typically 20% cheaper than TruDesign. (approx £36 for all three items compared with just under £50)

 

[KompetentKrew]

TruDesign are BSP so you need one size smaller than you think you do.

Consolidated Brass | CB Ideal Tapware

 

[Marceline]

You dont seem to have a seacock fitted? Will,the wash hand basin not flood when you lean over?

that's what the surveyor suggested - I was looking at various seacocks and the skin fittings to go with and was thinking of the trudesign (but will check out other suggestions like DZR like Tranona suggested)

 

[Marceline]

Yes, you are measuring the wrong part. That looks like a 13mm (1/2") hose which is common for a sink waste, but maybe 3/4". As it is just above the waterline it should really have a ball valve (seacock) on it. Suggest you take it out and measure the inside bore of the hose and buy a DZR ball valve with a hose tail of that diameter and a matching skin fitting. You can of course use TruDesign but it is really not necessary as either will last indefinitely and DZR is typically 20% cheaper than TruDesign. (approx £36 for all three items compared with just under £50)

thanks Tranona - will check when we go back at the weekend. We were hoping to have about 4 weeks to get these sorted but were informed that our boat is likely amongst the first to back in so we may only have a couple of weekends - so I think I'll try and 'best guess' these based on people's suggestions and if not order in the right parts for next weekend

 

[Marceline]

If the current plastic fitting is loose, I’d definitely be removing it. Trying to reseal it in situ is never going to be satisfactory.

thanks so much - that's good to know (will make this our number one priority to replace them now)

 

[Marceline]

TruDesign Domed Skin Fitting - 6 Sizes
View attachment 152589

oh wow - that's very handy - thanks for sharing

 

[Marceline]

thanks everybody - reading through the suggestions and comments think we'll head back to the boat at the weekend and try and remove the skin fitting and then mearsure what the hole diameter is.

just wondering, is there a way to just seal the hole up safely (maybe as a temp job for this year's season, and put the seacock/skin fitting in next year - just we might not have much time before the boat has to go back into the water) ?

 

[geem]

thanks everybody - reading through the suggestions and comments think we'll head back to the boat at the weekend and try and remove the skin fitting and then mearsure what the hole diameter is.

just wondering, is there a way to just seal the hole up safely (maybe as a temp job for this year's season, and put the seacock/skin fitting in next year - just we might not have much time before the boat has to go back into the water) ?

It will only take an hour

 

[john_morris_uk]

Putting a new skin fitting in an existing hole is a matter of minutes not days. It would take far longer to bung the hole up (unless you’d be happy with a softwood bung hammered into it for the summer and no sink to use…)

 

[LittleSister]

thanks everybody - reading through the suggestions and comments think we'll head back to the boat at the weekend and try and remove the skin fitting and then mearsure what the hole diameter is.

just wondering, is there a way to just seal the hole up safely (maybe as a temp job for this year's season, and put the seacock/skin fitting in next year - just we might not have much time before the boat has to go back into the water) ?

The hole size is the incorrect place to start (contrary to Boathooks's post #9 above).

To do it correctly, you start with the hose size, then buy a skin fitting sized for that, then make the hole in the hole to fit that.

Almost certainly your correct sized fitting in brass, bronze or of Marelon/Trudesign type will need a larger hole than the cheap plastic fitting than you currently have. It is likely because the plastic fitting is thin and not strong enough (and the type of plastic prone to degrading) the your surveyor has suggested you change it.

It is true that there's nothing to stop you buying a fitting narrow enough externally to fit in the existing hole, but then you will find you need a narrower hose on the skin fitting than that which exits the basin, and need a reducer to connect them. This will result in slower draining of the basin and likely occasional blockages at the point where the hose size is reduced.