DE23 potential oversize problem

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TomW1
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Re: DE23 potential oversize problem

Post by TomW1 »

I do not have the plans for the DE23 but on most plans they show the limber holes in the frames to drain to the transom and then to the pump and where to place the foam. On a boat the size of the DE23 I would recommend a pump with a capacity of no less than 1500GPH even 2000GPh would be good.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

wildbriz
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Re: DE23 potential oversize problem

Post by wildbriz »

Thanks, I have looked on the plans and from what I can see there are no markings for limber holes or foam locations unless I'm missing something. Some of the DE23s in the gallery are shown with buoyancy foam under the soles but I'm not sure if foam is really necessary and limber holes? Maybe I should submit another topic question.

TomW1
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Re: DE23 potential oversize problem

Post by TomW1 »

Check in B-239 Details and also Specific building notes for this boat. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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BarraMan
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Re: DE23 potential oversize problem

Post by BarraMan »

For what its worth, all the compartments under the sole of my boat are filled with closed cell polyurethane foam, except for those along the keel where the gas tanks are located. I also believe that the foam-filled compartments should be air tight, although I have no way of proving that. They don't have limber holes. The compartments along the keel that contain gas tanks are connected by limber holes and drain into the bilge.

I toyed around with making the boat self-draining, but ended up putting that in the "too hard" basket. I did put two large drains in the cockpit floor that drain into the bilge where there are 2 x LARGE capacity auto/manual electric bilge pumps and a smaller manual electric pump right on the bottom of the bilge.

Being a "belt and braces" kind of guy, I have a manual (ie man powered) bilge pump mounted at the rear of the cockpit.

I don't go off shore much or very far, but the Gulf of Carpentaria where I fish is shallow and can get very rough, and I have taken waves over the bow on a number of occasions resulting in about 6" of water in the cockpit. It rapidly drains into the bilge where the pumps kick in automatically and rapidly pump it out.

My boat is essentially double-hulled with foam between the hulls. By my calculations it is unsinkable and I believe it is likely to remain upright if completely swamped - but I have not tested that! 8O

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Re: DE23 potential oversize probl

Post by OneWayTraffic »

When I cut my transducer hole in the bottom of my boat near the transom I threw the 100mm plug into water. It floated, just. This part of the hull is nearly worse case in a sense. Thin plywood, glass both sides and aluminium filled epoxy coating. A hull that floats there will float in general.

After drying it out I took the plug to work and had the tech teacher put it in a vise. It took multiple hard hits with a hammer to break it. Even then the plywood delaminated internally and the glass stayed mostly intact. This was clamped into a vise, so no room for the plug to absorb energy by flexing. These hulls are light, and tough.

Matt Gent
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Re: DE23 potential oversize problem

Post by Matt Gent »

Search around and you will find plenty of threads on how to manage the bilge. In my case, they were clearly not airtight, and I almost sunk in the tortugas. I prefer limber holes. My boat currently has a few thousand plastic balls for water displacement in the bilge, and limber holes between all the cavities.

Water finds a way.

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Re: DE23 potential oversize problem

Post by OneWayTraffic »

Summing up the options comes to either foam filled and sealed or open with limbers and a pump. If you foam and seal everything then there is no bilge to install a pump into. Leaks usually come from chase tubes etc, so if you have zero penetrations to below this is an option. Foam entirely below the sole could cause the boat to turn turtle if it was ever swamped, as unlikely as this is in a DE23.

You can combine options as well. I have some foam in most of my compartments but the lowest part of them are either limbered, or accessed from above with a inspection port or plug. I used some rigid polyurethane foam to form a dam for the foam to retain the pour foam. I’m aware of the risk of water entry through a port and have most of them where water will not normally gather. My boat is also trailered, which helps.

It’s up to you but if I had any empty space under he sole I’d not sleep well if I couldn’t check it.

wildbriz
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Re: DE23 potential oversize problem

Post by wildbriz »

Thank you everyone for your help, it is greatly appreciated. I will look at foaming most of the under sole hull and probably just leave the compartments nearest the transom with the fuel tank feeding to a bilge pump.

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Re: DE23 potential oversize problem

Post by pee wee »

OneWayTraffic wrote: Wed Oct 12, 2022 3:01 pm Foam entirely below the sole could cause the boat to turn turtle if it was ever swamped, as unlikely as this is in a DE23.
You made some good points, but this statement doesn't sound right- whether it's a sealed air filled compartment or is foam filled, both weigh less than water. That does bring up the point that you should add flotation higher than the bilge, maybe under the side decks and under the cabin overhead, to provide upright flotation in an emergency.
Hank

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Re: DE23 potential oversize problem

Post by OneWayTraffic »

pee wee wrote: Fri Oct 21, 2022 9:29 am
OneWayTraffic wrote: Wed Oct 12, 2022 3:01 pm Foam entirely below the sole could cause the boat to turn turtle if it was ever swamped, as unlikely as this is in a DE23.
You made some good points, but this statement doesn't sound right- whether it's a sealed air filled compartment or is foam filled, both weigh less than water. That does bring up the point that you should add flotation higher than the bilge, maybe under the side decks and under the cabin overhead, to provide upright flotation in an emergency.
I meant that any kind of buoyancy below the sole would have that effect, no matter what’s it’s made of. While buoyancy to the sides and higher up works against the free surface effect of water.

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