Can I do this??

The watery and smelly sides of life.
Catalyst60
Posts: 29
Joined: Mon Jun 23, 2008 4:47 am
Location: Brisbane

Can I do this??

Post by Catalyst60 » Fri Sep 18, 2009 3:32 am

Why not ask a marine surveyor in your area?

DT

mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Can I do this??

Post by mahnamahna » Fri Sep 18, 2009 3:54 am

I have access to 3 different shipwrights, I will ask them all, but shipwrights are a little like economists, if you get 5 in a room and ask their opinion you get 6 different opinions. It turns out that poly pipe is poly ethylene but that many of the fittings are polypropylene. Cheers, Paul

Smooth Cruiser
Posts: 583
Joined: Thu May 11, 2006 1:51 am
Location: Brisbane

Can I do this??

Post by Smooth Cruiser » Fri Sep 18, 2009 5:02 am

Polyethylene (black irrigation pipe you are talking about) is fine in salt water and quite resistant to UV. It is used by dredging operations, oyster farmers etc as you say. I use a length as a tiller extension for my dinghy outboard and it sits in the sun and salt water all day for the last seven years.



Having said that though - why not use flexible pipe? I am a bit anti any stiff pipe in a boat - all it takes is something rolling around in one of your cupboards and it can knock the pipe off the fitting, cause it to leak or with PVC shatter it. Flexible pipe has more give and can handle knocks etc as well as flexing of the boat without as much drama. Also much easier to take apart later on - just pull the hose off the fittings. If you hard pipe it (glued joints) then you probably end up having to cut the pipe to remove it. Even if you put flanged fittings (screw together, victaulic or bolt together flanges) it is much harder to take apart and then line up again for reinstallation. Just a thought.

mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Can I do this??

Post by mahnamahna » Fri Sep 18, 2009 5:27 am

Hi Smooth, thanks for that info. I suspect that Poly pipe might in fact be the perfect compromise pipe. My concern with flexible hose was that all hose eventually perishes. So I thought for the sewer out I would use the normal white rubber reinforced sewer hose from the toilet up to the tank, and from the tank down to the stopvalve, then from the other side of the stopvalve to the through hull I thought I should glass solid pipe into the boat (only about 300mm) so that I can stop the valve to replace hose down the track, so that it can be done without hauling out or somehow plugging that through hull. I think I have my solution now though.



I would still like to hear if $25 per meter is the going rate for the flexible 1.5 inch sewer hose. I need about 10 meters I think. (2 toilets, 2 tanks, 2 through hulls, 1 in each hull).



Cheers,



Paul

Smooth Cruiser
Posts: 583
Joined: Thu May 11, 2006 1:51 am
Location: Brisbane

Can I do this??

Post by Smooth Cruiser » Sat Sep 19, 2009 2:40 am

Try Enzed hoses for a comparitive price - they have all manner of hose wall thicknesses, diameters etc. They are not the cheapest but in my experience they are one of the few places you can walk into that will have exactly what you want in terms of flexible hose.

mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Can I do this??

Post by mahnamahna » Sat Sep 19, 2009 6:22 am

Thanks Smooth, I hadnt thought of Enzed, I will check them out.



I wont need hose or pipe between the through hull and the stopvalve after all. After putting all of the fittings together they set up exactly how I wanted anyway. This is going to be my set up:







The only part not on there is the bronze through hull and onto each of the ends will go the 2 hoses clamped on, from the 2 tanks, the larger 1.5 inch being the black the smaller 3/4 inch the grey, but I may increase the gray out hose to 1 inch. I have them joining before the valve so I only need 1 through hull for both outfalls. All of that gets mounted inside the vanity cupboard under the shelf and behind a door.



And all of those fittings cost less than $50 from the local irrigation supplier about half the price BIAS wanted.

44c
Posts: 1148
Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Can I do this??

Post by 44c » Sat Sep 19, 2009 6:00 pm

The valve you have there is very cheap, but I'd spend more on a better one if I were you. Those valves are quite stiff to operate even when new, and they get MUCH worse.

mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Can I do this??

Post by mahnamahna » Sat Sep 19, 2009 6:16 pm

I am not doubting you 44 but I was told by a cruising friend to go for plastic because salt water makes the bronze ones seize. This one is not very stiff to open or close, and is exactly the same as the one I saw at BIAS.

44c
Posts: 1148
Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Can I do this??

Post by 44c » Sat Sep 19, 2009 11:30 pm

BIAS actually sell BRASS valves too, which are totally unsuitable for marine use, so the fact that they stock them is no recommendation.



I got plastic too, but superior quality Hansen valves. An irrigation place should stock them. They're not cheap, probably around 4 times the price of the PVC one you have, but they should last forever, and stay easy to operate and in the scheme of a boat costing around $200K, the price difference is inconsequential.

madaz
Posts: 527
Joined: Thu Apr 26, 2007 7:47 am
Location: Hobart, Tasmania

Can I do this??

Post by madaz » Sun Sep 20, 2009 3:47 am

Paul, I echo Alans opinion on those particular plastic valves. I have no experiance with them in terms of failure but a number of builders here who have built a couple of boats wont go anywhere near them and steered me to Philmac Valves.



You can buy philmac valves also, not sure how they compare with the one Alan mentions, you can buy them at rural supply/irrigation shops. MUCH MUCH better

pic below


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