Scupper ?

[duysall83]

Hello all, probably its sth very common but please tolerate my ignorance.

Searched many but once u have no fundamental its not easy to understand the basic logic. Mostly explanations on web assume the reader has enough info for a beginner. I may be the outlier

So i need your help.

Ok scupper is sth to drain water from boat. Number 1 on the picture, is it a common application for sole drainage? A drain plug on sole and hose connected to outlet plug on transom and can be above and also below waterline (because of check valves etc that plug has?) Hose is a must for that setup, right? That hose should merge with other hoses from other scuppers? Or each should have individual hoses?

For number 2 and 3. I see on pics at other threads that there is some plug on side decks such as number 3, and a hose seen from inside which connects the plug on side deck (3) to a hole on position 2. What is the purpose? Or i got the setup wrong? And also that plug i guess just a hole without any backflow prevention? Since its well above waterline?

For number 4. Should there be any more drains from below sole, close to hull bottom? If yes, do we expect water to flow towards outlet plug via gravity?

Sorry again for my ignorance and probably silly questions, please comment if you have time. I dont have enough time those days for detailed research thats why i ask, i need shortcuts at least for now.

Thanks in advance

Duysal

[Fuzz]

Scuppers drain the water off the deck. They can be out the sides or the transom. They drain water overboard and not into the bilge. I would not use drains with hoses below the waterline. Any type of check valve can and will leak at some point and that could be very bad.

[TRC886]

If I'm not mistaken, scuppers are usually cut through the hull sides, near the transom, and are just above the sole. They have a one-way valve, and allow for the boat to be self-bailing. A flapper valve is common. Will you get minor water intrusion through them? Probably, but not enough to worry about. Note that the sole must be above the waterline.

I posted a link, but took it down because BBC might stock them. Check here first, and look at a pic. This'll help clarify what I'm talking about.

[Crystal Craft]

Hi Duysal
Your not alone here!! I’m right at that point in my Panga 25 build. I’ve read so much on water flowing back into boat and the valves don’t seem well..”perfect”. And I’m in Northern Lake Michigan so we’re talking ice water here! So cold it hurts!
My motors total 300 lbs a 60 + 6hp not a huge load on transom.
I think I’ll put two transom type drains on the back with hoses to outlet open at transom with some kinda check valve and could also have drain plugs cockpit sides. Would be about 7 in above bottom of boat at transom. Straight if drain down then out Ide suspect water back flow. Making the outlets lets underwater at my transom Ide think I’ve also seen simple transom drain plugs off the sides? Add two of these that could be 4 outlets? At 1 in each? Are bigger ones available? Ie 2 in? It seems like not enough outlet volume? If I take one over the bow Ide like it to drain fast not watch it slowly leech out? Maybe the goal is not for that capacity outflow? I’m not sure. I thought to add a bilge pump or 2? In cockpit area maybe 1100 gpm As you can see I’ve got more questions than answers as it stands now I’ll just do two straight out transom with check valves and plugs at cockpit. Thinking I can add sides and pumps later.
Steve
Crystal Craft
Michigan 33 degrees

[duysall83]

Hi Duysal
Your not alone here!! I’m right at that point in my Panga 25 build. I’ve read so much on water flowing back into boat and the valves don’t seem well..”perfect”. And I’m in Northern Lake Michigan so we’re talking ice water here! So cold it hurts!
My motors total 300 lbs a 60 + 6hp not a huge load on transom.
I think I’ll put two transom type drains on the back with hoses to outlet open at transom with some kinda check valve and could also have drain plugs cockpit sides. Would be about 7 in above bottom of boat at transom. Straight if drain down then out Ide suspect water back flow. Making the outlets lets underwater at my transom Ide think I’ve also seen simple transom drain plugs off the sides? Add two of these that could be 4 outlets? At 1 in each? Are bigger ones available? Ie 2 in? It seems like not enough outlet volume? If I take one over the bow Ide like it to drain fast not watch it slowly leech out? Maybe the goal is not for that capacity outflow? I’m not sure. I thought to add a bilge pump or 2? In cockpit area maybe 1100 gpm As you can see I’ve got more questions than answers as it stands now I’ll just do two straight out transom with check valves and plugs at cockpit. Thinking I can add sides and pumps later.
Steve
Crystal Craft
Michigan 33 degrees

Glad to know im not alone but even your questions are a little advanced for me at that moment. ))) I was trying to get the main concept, not the flow, drain capacities etc. Even with 3 replies i got some piece of info which is good. Thanks, good luck on the build.

[fallguy1000]

I profess zero expertise beyond reading. Scuppers in the classical sense of the word are best used when the deck or sole are well above the waterlines.

And therein lies the problem.

In a small craft like a Panga, if the scuppers are only an inch or three above the waterline; any heavy loading results in wet feet.

My take on them is that the best way to go is dual. A bilge pump or drainwell first. Later, if you develop a confidence about the lines; adding a scupper or two seems good. Or, even planning the scuppers, but not breaking into them or leaving them capped until that confidence is established seems wise.

[OneWayTraffic]

Here's a link to my scupper holes.

download/file.php?id=14944&mode=view

Large holes in the transom 75mm in diameter. Just at the expected level waterline. I plan to epoxy in a short fibreglass pipe and clamp a length of hose to that. The design is common on ribs and is called a duckbill or elephant trunk scupper. Some photos of what it looks like on this linked thread.

https://www.fishing.net.nz/forum/irbs-f ... 77151.html

They dump water very fast if the boat is moving forward, which is why they are on IRBs (Inflatable rescue boat) designed in NZ for breaking surf conditions. The IRBS also have a couple of small ball valve bailers to clear the little bit left in the bottom.

My plan is to have a setup with a large sump at the back by the transom. Pump in it and the scuppers over the sump.

Any backflow is caught into the sump, so my feet stay dry. If I should ever take a large volume of water the scuppers will clear the bulk of it fast down to the level of the holes. I intend to have some buoyancy along the sides for stability.
The pump at the bottom of the sump will clear water in normal use. I can also put some holes in the sides if I want to.

I would not recommend any kind of through hull where it can not be seen from the cockpit.

[TomW1]

There are various ways to get rid of the water off your sole. Most small boats don't even worry about it and you use a coffee can if needed, ie. the GF16. Self bailing really doesn't come about to 18' and above. My preferred way is out the transom here are some scuppers from Hamilton Marine that do the job. https://shop.hamiltonmarine.com/inet/st ... D=scuppers Just run a tube from the opening in the front of frame E to the transom and the scupper. Every thing is above the sole. Others direct the water to the bilge and allow the bilge pump to pump to it over board. Make sure you have a duplicate pump and battery if you go this way they have been known to fail. Most of Jacques boats above 20' have a sole well above the water line and there is no problem using a scupper out the transom.

The main thing with scuppers is you want to get a lot of water off your boat before the next wave comes over the bow in a storm if you should ever get caught in one.

Tom

[Fuzz]

When you are trying to clear water off the deck scuppers can not be too big. I have a boat with 4 four inch scuppers. I have seen times when they were not big enough but 4 inch is as big as I can get plugs for.

[OneWayTraffic]

You could always get a round inspection port with a screw lid. They get up to 8" in size. Seems overkill to me and it will weaken the side and look like crap but if you need to really clear a deck...