Cockpit scupper tubes using G10

I am doing a major restoration of a Cabo Rico 34 (including replacing all bulkheads with Coosa) and plan to use G10 fiberglass tube as the cockpit scupper drains and glassed-in thru-hull (I do not plan on using bronze thru-hull or seacock). Of course, the hull exit point will be ground and bevelled, with a robust glass layup joining the tube to hull, using epoxy and 1708. Same with the cockpit. I plan to use G10 2" ID tube for fast drainage, and either 2.5" or 2.75" OD for structural tube strength. Since the cockpit scuppers are positioned just behind the aft-cabin bulkhead - which is currently uninstalled - I have options: 1) implement bulkhead and scupper/tube/thruhull as a combined structural unit, as a straight shot down from the cockpit using a full length of G10 from the cockpit to the hull, and glassing the G10 tube along the bulkhead so the whole structure is integrated, and any hull flexure will occur away from bulkhead/tube. Option 2: Glass a section of G10 as a thru-hull above the waterline and a foot or so aft of the scupper (about a 45-degree drop from the scupper), with corresponding G10 section glassed to the cockpit as the scupper itself and pointed aft/downward, with both pieces connected by hose to accommodate flexure. I know both options have been implemented by modern builders, and ABYC allows for this type of installation. I plan to move forward with some iteration, or somewhere between option 1 and 2, and am asking for design advice to ensure ideal and proper installation. Thanks in advance.

 

Both options sound very reasonable really.
Can you post some photos please of the area where these drains will be installed?

Re how you are replacing all of the bulkheads with Coosa, how many of these have been completed so far?
I think that if you incorporated your question re the cockpit drain tubes into a rebuild thread describing the other aspects of your rebuild as well, it would be well received on this forum.

 

I prefer no hoses.

However, I don't understand whether you have access to both sides of the tube on option one and I don't like holing a hull right next to a tabbed bulkhead or thru the tabbing.

So, really a napkin sketch would be needed for me to render a good opinion.

 

I don't know how long a 2" ID tube will take to empty that cockpit.It would empty a great deal faster if you used larger tubes and ran them out through the transom.It might also annoy the neighbours in the marina.Something like this drains even faster but was designed from the outset with the scheme in mind.
No leak potential at all.

 

Here is a GA drawing of the Cabo Rico 34 from Sailboat data.
SailboatData.com - CABO RICO 34 Sailboat https://sailboatdata.com/sailboat/cabo-rico-34



We have a similar type of long keel 35' boat, but with a much narrower transom - she originally had two 1.5" diameter cockpit drains draining through seacocks in the hull bottom. But this meant that the seacocks had to be left on all the time at her mooring, so that rainwater could drain out, which then led to them seizing up, even if I 'worked' them (or tried to) each time I visited the boat.
So I fitted two 1.5" drains going out of the back of the cockpit, to through hull fittings in the hull sides, that are above the waterline. These work well, however water does come in through the leeward drain from outside when the boat is heeled while sailing.

What was the previous set up re the cockpit drains in your boat? What diameter are they?
Two 1.5" diameter drains have a total cross section area of 1.77 square inches, and one 2" diameter drain has a cross section area of 3.14 square inches - so even just one 2" drain would be a 75% increase.

 

Thanks for the responses - feedback is all appreciated. Here are some photos of the bare project which should offer some idea of my thought process. Aft cabin bulkhead is removed, and the tabbing (mostly ground away) still reveals the line where the bulkhead is tabbed to the hull. The top of the aft bulkhead is tabbed to the aft cockpit well, where it is rounded over (under? inverted? IDK). The current scuppers do a 90-deg turn to horizontal, but I plan to remove those and install a section of 2" G10 tube vertically (option 1) or diagonally (option 2 or in-b/t). The current hose installation is just a temporary solution to provide drainage during the project, but does give an illustration of how the boat was manufactured - the deck drainage tied into the cockpit drainage - all exiting through two 1.5" thruhulls. I haven't described my plan for the deck drainage, but it will essentially be option 2 described above, just separated from the cockpit drainage. Focusing on the cockpit drainage, installing bigger tubes horizontally to drain thru the transom, or creating an open transom, is not compelling to me (though I appreciate the suggestion!), mainly for aesthetics (I don't want to commit to a stark redesign of the lines) - but I appreciate the effectiveness of those approaches. I am pretty decided on using the G10 as I've described, but how?

@Banjansailor I did the exact same drainage install on my Ericson 29, and don't mind the water coming in leeward drains while sailing. We are sailing after all...

 

Here are a few more photos of the project. The boat survived Hurricane Andrew, but was stove in on the port quarter in a pileup of moored boats in the Bahamas (7 of them were Cabo Ricos, all still sailing today -except mine... yet. Other boats in the pileup were battered by the CR's apparently). The PO repaired it, but over time, those repairs developed cracks (all done in polyester and plywood with a lot of gelcoat). The bulwark repair was the main culprit for water getting into the boat and damaging cabinetry, but other hull-deck joint areas also offered ingress. I removed/ground away all of the prior repair, and what you see is my epoxy/1708 repair to the bulwark, and deck area, and will move on with the the cockpit coaming soon. All bulkheads had to be removed because there was about a foot of water in the boat for years, and it was all running through the cabinetry and down the bulkheads. Also, the humidity that existed in the boat while it had significant water in it did a fine job of delaminating all the plywood. The cabinet facades are all salvageable, and after the coosa bulkheads are reinstalled along with refinished door frames, the refurbished cabinets go back in which are all modular. I make it sound so easy... Hmmm

 

All that work and access and you don't want some nice big transom tubes?

That would be my plan. I'm with wet feet here. I have pvc tubes in my boat bonded in with Black Mamba FHG. Untested, but I'm told should work. The appearance side is pretty, but the back side is laid on thick.

 

I'm not liking what I see in there. Single hose clips and a Y-piece in the line, together with no seacocks and on top of that there are abrupt 90 degree bends. An improvement is definitely in order. Have you any idea how long it would take the cockpit to drain? Or the total weight of water that it might contain? These factors need to be kept in mind when adding sufficient structure to support the weight and efforts should be made to reduce the time taken to drain.

 

@fallguy I hear ya - and think option 2 is essentially that. As @bajansailor pointed out, even 1x 2" tube increases overall OEM drainage by 75% (and that is a modest estimate bc the OEM deck drainage tee-d into the cockpit drainage, and mine won't). Wouldn't 2x 2" drains above the waterline (but not on the transom) do basically the same thing? My only worry with stern drainage tubes is an overtaking wave will push water into the cockpit, whereas drainage at the cove (on quarters before transom) at least has has a little buffer from the shock of an overtaking wave.

@wet feet Not to worry - those hoses are only temporary so cockpit and deck can drain during the project (they are actually swimming pool hoses - cheap!), and will be there until I sort out what I'm going to do with G10 tube. Best solution - a pole barn covering the whole thing...

 

Option 2. With option 1, no matter what you do it will flex, fiberglass itself is not a stiff material, and also flex between the hull and deck…..will result in the tubes cracking at some point….

 

They make scuppers with all sorts of varying valve methods if you want to one way them...

If you run out the back; the distance may require some support. I can't tell if it is 4 feet or 2 feet. Even the angle of the existing tubes looks almost perfect to carry to the transom...

 

I am leaning towards option 2, and agree that option 1 (bonding tube to bulkhead) limits access should something fail and need to be addressed in an emergency. Attached are a couple of photos of interior lazarette, and exterior quarter at waterline, with markup (in black) showing approximate places where 2" tube would be installed with hull. I know the markup is rudimentary, but wanted to illustrate 2 things - 1) placement of the g-10 thru-hull is within 18" of the (to be installed) G10 scupper which will be oriented 35-45 deg downward, and 2) the G10 thru-hull will be oriented to hull at an angle (pointed upward and forward to the scupper), so the hole itself will be oval in shape where it meets the hull. The scupper and the thru-hull would be connected (double clamped ) using durable but moderately flexible hose to accommodate a 2" ID/2.75" OD hose (silicon?) over a short span ~ 18". On the exterior photo, never mind the white strip fastened above the cove stripe. That is a router guide to strike a shallow v-groove waterline mark and will be removed of course once bottom job is completed and waterline mark is struck. The oval shape is approximately where profile of G10 thru hull would match up with the interior and exterior photos. Use the propane locker thru-hulls as a benchmark for rough positioning of thru hull in both interior and exterior photos.

@fallguy Your arguments are compelling. For my application, going back thru transom would encroach on steering cables, including hydraulic RAM for autopilot. There is some room back there, but once that stuff is installed it gets pretty tight pretty quickly. I think in my application, moving drainage away from steering systems is necessary. Appreciate your input!