Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 15-09-2022, 20:11   #1
Registered User
 
phorvati's Avatar

Join Date: Jan 2006
Location: Rhode Island
Boat: Tayana FD-12
Posts: 1,199
Images: 6
manual diaphragm bildgepump discharge though hull above or below waterline?

Mine is discharging below waterline. Is there a reason for this?
I am hauling out for some maintenance. I am going fill and glass over old 1-1/2" through hole for head discharge (i switched to composting toilet and no longer need it). I am also addressing 4 bronze Apollo valves threaded onto though-hull by adding adapter plates so things are not cross threaded.

One of Apollo valves threaded into 1-1/2" through-hull services a hose for manual diaphragm emergency bilge pump.
Can't that discharge above waterline? I would gladly plug two 1-1/2" though-hulls.
phorvati is offline   Reply With Quote
Old 15-09-2022, 22:07   #2
Registered User

Join Date: Aug 2021
Location: PNW
Boat: 35 Ft. cutter, custom
Posts: 2,524
Re: manual diaphragm bildgepump discharge though hull above or below waterline?

Quote:
Originally Posted by phorvati View Post
Can't that discharge above waterline?
Absolutely!
Underwater discharge increases pumping effort and slows down the flow.
It also adds another potential leak/flood point.
By all means go to an above waterline discharge.
__________________
Beginning to Prepare to Commence
Bowdrie is online now   Reply With Quote
Old 15-09-2022, 22:57   #3
Moderator and Certifiable Refitter
 
Wotname's Avatar

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 20,978
Re: manual diaphragm bildgepump discharge though hull above or below waterline?

IMHO - always above (well above) the waterline or into a self draining cockpit.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 16-09-2022, 09:13   #4
Registered User
 
phorvati's Avatar

Join Date: Jan 2006
Location: Rhode Island
Boat: Tayana FD-12
Posts: 1,199
Images: 6
Re: manual diaphragm bildgepump discharge though hull above or below waterline?

Nice. So I don't suppose someone can point me to write up on plugging 1-1/2" holes with polyester. I will try to get to 12:1 bevel as best as I can, I have heavy glass tape from when I was rebuilding my bulkhead in 2017. I wonder if resin is still good.
phorvati is offline   Reply With Quote
Old 16-09-2022, 10:25   #5
Registered User
 
Sailor Sailor's Avatar

Join Date: Aug 2021
Location: Glen Allen, VA
Boat: Sabre 34-1 CB, 34 feet
Posts: 342
Re: manual diaphragm bildgepump discharge though hull above or below waterline?

You must use epoxy resin, not polyester. There is a good explanation of how to do this in "This Old Boat" by Don Casey. After beveling, clean with acetone. Basically, you attach a nonstick surface, for instance waxed plasticine, to the inside so it conforms to the curve of the hull, then apply multiple layers of woven cloth and resin over the hole on the other side, covering the bevels and extending out beyond the circumference of the hole.

For each layer wet the surface with epoxy on a paintbrush, apply the cloth, remove bubbles, and repeat until you have about 5 layers. Wipe up drips of epoxy resin. It should generate heat as it cures. When cured but still tacky, repeat with more layers until new layers cover beyond bevelled surface on the outside. Then remove the nonstick surface on the inside and apply more layers to the other side until bevelled surface is covered. Use a sanding grinder to smooth and paint.
Sailor Sailor is offline   Reply With Quote
Old 16-09-2022, 10:45   #6
Registered User
 
phorvati's Avatar

Join Date: Jan 2006
Location: Rhode Island
Boat: Tayana FD-12
Posts: 1,199
Images: 6
Re: manual diaphragm bildgepump discharge though hull above or below waterline?

Quote:
Originally Posted by Sailor Sailor View Post
You must use epoxy resin, not polyester. There is a good explanation of how to do this in "This Old Boat" by Don Casey. After beveling, clean with acetone. Basically, you attach a nonstick surface, for instance waxed plasticine, to the inside so it conforms to the curve of the hull, then apply multiple layers of woven cloth and resin over the hole on the other side, covering the bevels and extending out beyond the circumference of the hole.

For each layer wet the surface with epoxy on a paintbrush, apply the cloth, remove bubbles, and repeat until you have about 5 layers. Wipe up drips of epoxy resin. It should generate heat as it cures. When cured but still tacky, repeat with more layers until new layers cover beyond bevelled surface on the outside. Then remove the nonstick surface on the inside and apply more layers to the other side until bevelled surface is covered. Use a sanding grinder to smooth and paint.
Boat is laid up in polyester. I have epoxy barrier coat that i will put on the outside to any exposed areas. If boat was done using epoxy, I would use epoxy, since its polyester, other than strength, I don't see a reason for epoxy. Its stronger, but also more expensive, harder, more time consuming to work with.
phorvati is offline   Reply With Quote
Old 16-09-2022, 20:02   #7
Registered User

Join Date: Mar 2010
Posts: 204
Re: manual diaphragm bildgepump discharge though hull above or below waterline?

Polyester is fine, why mix apples with oranges?
You might consider saving a thru hull, just in case you develop a need for more water at a later date. It could be plugged for now.
kapnd is offline   Reply With Quote
Old 17-09-2022, 05:19   #8
Registered User

Join Date: Oct 2019
Location: Kennebunk ME
Boat: Owner built 60í Aluminum Expedition Yacht.
Posts: 1,854
Re: manual diaphragm bildgepump discharge though hull above or below waterline?

Buy a nipple and carefully examine the threads on the valves. A new valve is not going to ruin your new adaptor plate. Screwing in a nipple into your old valves by hand will give you a feel for the threads. Pipe taps are expensive but maybe you can borrow one. Donít over cut the female threads. A tap will chase out tiny defects but if the old valves have bad threads itís better just to dump them.
We would only use epoxy and triaxial glass.
The manatee crew
Manateeman is offline   Reply With Quote
Reply

Tags
agm, diaphragm, hull, pump, water

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
380: Flex in Lagoon 380 hull below waterline MTF Lagoon Catamarans 25 21-03-2022 07:40
Advice on boat purchase with hull work evident above the waterline Kris V Dollars & Cents 6 05-09-2020 12:21
Blackwater discharge above the waterline? GILow Plumbing Systems and Fixtures 55 16-11-2019 00:37
Cockpit Drain Above or Below Waterline? Paul Mazza Plumbing Systems and Fixtures 21 03-10-2017 10:44
AC discharge thru-hull: below waterline, or piss off my neighbours? Geoff S. Plumbing Systems and Fixtures 16 24-04-2008 07:24

Advertise Here


All times are GMT -7. The time now is 13:59.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.