Cockpit Drains

[Darren]

I have 1972 Islander 30. Pretty sure it was made after January, and wanted to know how many cockpit drains I need. I already upgraded the original drains with the two 1.5" with ball check like the ones in the link below. From what I read I need 4 @ 3/4" can anyone help me out with this? Also thinking about getting transom drains with flappers. I used to have water "coughing" up my drains and was thinking this would stop it. The balls are stopping it but they can get push up and then the cockpit doesn't drain.



Thru Hull Scuppers I'm looking at
https://www.westmarine.com/buy/perko--t-hull-scupper-1-5-inches--2359149?recordNum=9

Cockpit Drains I installed (do i need 2 more?)
https://www.amazon.com/BJTDLLX-Stainless-Marine-Scupper-Fishing/dp/B09P5ZXWQX/ref=sr_1_53_sspa?crid=YZ243OA2ANK9&keywords=Deck+Drain+Scupper+With+Ball&qid=1645494239&sprefix=deck+drain+scupper+with+ball%2Caps%2C222&sr=8-53-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExUDIyV0JWREwyN0hBJmVuY3J5cHRlZElkPUEwMDg5NjA5UjRWMDNFTVo0WFpWJmVuY3J5cHRlZEFkSWQ9QTA3MDQ5ODhZMFVNSUxKUTJXQzkmd2lkZ2V0TmFtZT1zcF9idGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

 

[BobJ]

You shouldn't need the stern flappers if the drain hoses are run properly (and kept clear). Usually the hoses are crossed underneath the cockpit (port drains to starboard and vice-versa). I have those same drains with the balls inside. The balls do get stuck so you need to keep them cleaned out.

As to how many drains you need, the typical requirement is they need to drain six inches of water out of the cockpit in five minutes. Get a big bucket and test it out.

 

[Darren]

Thanks. I wasn't sure if there was a specific regulation to fallow for these kind of questions. Is there a good resource I can pull up for requirements? I was looking at the 2022-2023 Offshore Special
Regulations. I thought you only needed to cross drains if they didn't go out the transom. Seems kinda odd to drain water out the high side of the boat.

Any thoughts on running ridge PVC pipe for the bilge pump? I've seen some people connect the hose and exit with flex hose, but run PVC pipe from the bulk of the run? I know aircraft do something similar with there lines. It seems logical just not sure about the material. On one forum they suggested using CPVC (Chemical Resistant) to prevent oil and fuel leaks breaking it down.

 

[BobJ]

The Singlehanded TP and the Pacific Cup use the "six inches in five minutes" language, which comes from US Sailing's model SER for coastal and offshore races:

https://www.ussailing.org/competition/offshore/safety-information/ser-world-sailing-special-regulations/

My cockpit drains are downhill to through-hulls below the waterline. Your geometry will be different but you still shouldn't need the flappers. You have a production boat and the designer or builder would have worked this out - I'd inspect a sistership or two.

For bilge pump hose, typical is the corrugated flex hose because it's easy to run but the pump will be more efficient with smooth-walled hose. I'm using reinforced PVC (the clear stuff with red tracer) on my lower-capacity manual pumps. If you have fuel or oil leaks into the bilge you have bigger problems, and it should be removed from the bilge before running the pump.
.

 

[Darren]

Thanks for the link. I don't have oil or fuel in my bildge I think the thought was if at some point you do get it in the bildge your pipe will survive, or if you are going down and there's that much in the water it won't eat away the pipe. But yeah least of your problems for sure.