I am giving consideration as to what to do about my cockpit drainage. The existing system is 37 year old 1 ˝ inch gate valves and flexible tubing, 4 drains exit to two thru hull
Everything I read suggests including this thread, is that this sort of drainage scheme is way under sized. I used the online calculation tool referenced earlier in the thread to develop an estimate of how long it would take to drain my cockpit through a single
1 ˝ inch drain - about 8 minutes. Now, what I did is pretty crude. I estimated my cockpit volume, then I calculated the equivalent cylinder to match the tool which calculates for cylinders. I put in a length of 3 feet for hose length, and 3 feet for some other parameter, not even sure what it means, but it certainly isn’t the default 10 feet. Left all the other dozens of parameters to the default values. Out spits 8 minutes.
So for two 1 ˝ inch drains maybe my cockpit drains in about 4 minutes. Maybe.
To restore this likely inadequate situation is going to be a pair of seacocks at $90 each, backing plates
, silicon bronze screws, quite likely thru hulls, and presto I am likely at north of $400, for an inadequate solution.
Then consider a 4 or 5 inch diameter hard fiberglass
tube. I like this idea except for a few issues. One, I am not convinced a rigid structure isn’t going to find a way of cracking in the long term. Two, I want it to not be there in case I have to shoehorn my body down there to fix something in the vicinity one day. Repairs
are another reason it sucks to be a large guy around boats.
So what about a pair of barbed thru hulls of a substantial diameter? I have found 2 ˝ inch bronze instances for about $90, and 2. ˝ inches with the same crude estimate as above will drain in 3 minutes. A pair of these tubes has a figure of something like 1.5 minutes. Unfortunately, 3 inch parts
explode in cost to around $200 each. Maybe there is something in Marelon somewhere, but parts
start getting scarce over 1 ˝ inches. Then there is the small matter that I have not found a source of flexible hose in these diameters. Surely it must exist somewhere. So for about the same money
, I think I could eliminate two below the water line thru hulls, and about triple the rate of cockpit drainage. I could route
the existing cockpit drains through the transom too, just to keep rain at bay, and do that last bit of drainage when the bulk is gone.
Anyhow, these are my thoughts if anyone has anything to add.