Flooding keels on bertrams/hunts/haines

[member 65088]

Have just finished glassing new stringers into my hunt 18,
But have found some info that says these originally had flooding keels.

When dismantling the poor "renovation" that was done previously there was no sign of a flood compartment in the centre line.
Before i glass in the deck, is this something i should be putting back to add stability at rest, or are people not including such things in their repairs?

If im best putting it back in, what kind of height should the flood chamber be stopped at?

Thanks

 

[Mr Efficiency]

I would not bother, it is an unnecessary complication, the only one I've seen of the Hunt hulls with one, was a 15 footer, and even with some of those, they ditched it when re-built.

 

[Mr Efficiency]

This is a fishing boat commonly used by commercial line fishermen on the Great Barrier Reef, based on a slightly smaller ( 5 metre ) Hunt hull, no flooding chamber.

 

[IronPrice]

A company over here in NZ called Surtees uses flooding keels in their designs. They build deep vee alloy boats. They are reputed to work well in that application. Of course alloy hulls tend to be lighter, so thye have more propensity to rock at rest.

 

[fallguy]

Isn't bilge filling just done in rough weather?

These rebuilds are usually done in 3/4 ply to try to maintain DWL. Sort of heavier is good based on my reading.

The hack method is to open a drain plug, but I'd rather ride high n slow n take the pounding than start off the trip to 20,000 filling my bilge.

 

[BlueBell]

I drove a ~32' Bertram hull one summer as a tour boat.
No cabin, just an aft steering station and a dozen seats.
It had flooding water ballast and it worked great!
The added stability went a long way to calming roll when stopped
and self drained quickly when throttle was applied.
Great system.

 

[IronPrice]

Isn't bilge filling just done in rough weather?

The Surtees boats I referred to have keel compartments that flood from the transom and are vented to the anchor locker. At rest they flood providing lateral stability. When the boat is planing they empty.
The keel chamber also has a transom gate that allows the water to be retained when the boat is underway. This is handy in rough weather or when trolling in a quartering or beam sea. Also handy for tow-sports if a bigger wake is required.

 

[Squidly-Diddly]

Put a little hatch in transom to insert an air bladder to inflate and expel water prior to trying to get up on plane, or as extra flotation.

Use a FUEL bladder.

 

[BlueBell]

If designed properly, the chamber should begin emptying as soon as the boat starts moving forward, long before reaching "the hump".
Not really the best location for floatation.