twin or bilge keels

ongolo

ongolo

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I have a gaff schooner, but acquired a 5m life boat and would like to convert it to a sailboat. To be able to beach it, I would like to put bilge keels on, also called in some parts of the world twin keels. Anybody have any idea where to get design details for such a conversion?

Thanks.

PS, almost non of the old hands are visible on the formum
 
Guy used to have something similar in our club.
He cast the keels in sand, and used a Westerly pattern for keel width at hull joint and bolt pattern. Reinforcement plates inside. He also had a lot of iron ballast in ingots in the bilge.
Wouldn't go to windward, but it was a tough old thing.

Welcome back, havent seen you here for a couple of years. Did the boat get finished then?
 
Not quite the answer you seek, but..........

My old man had a Fairey Fisherman (27 foot motorsailor based on a lifeboat hull from a cancelled ship order in the 1960's). The original design was to (obvioulsy?!) retain the shallow centre keel with shallow added bilge keels each side. These (from memory) were in length about 2/3rd of the length of the boat, ie did not reach the ends of the boat, about equally. They were about 8/10 inches at their deepest (amidships) which meant that when drying out (which we do a lot in Jersey!) she listed at angle of around 30 degrees. Not dangerous, but more than enough to notice! / be glad very when she refloated!

The "Solution" was very simple adding short "stub" keels to the exsiting long shallow bilge keels, probably about 2/3 foot long. The idea being that the main keel had the weight of the boat, and the stub keels only propped the boat upright (maybe a 5 degree list?) with any load on the stub being spread through the hull by the existing long and shallow bilge keels. Bit of tapering on the stub for appearances / dynamic water flow efficiency /forums/images/graemlins/smirk.gif

Didn't affect her sailing performance, still sailed slowly /forums/images/graemlins/grin.gif

Will see if I can post a diagram! I hardly understand my own description!
 
G'day Neil (Magna Carter),

Quote

<<<upgrade has allowed username changes, so we're all rapidly becoming boatnames! >>>

Well I was thinking about renaming the boat 'Pride Of Oleron' after the small island on which the first agreement regarding the laws or the sea were signed back in the days of Richard the Lion Heart.

This would be bit too long to type every time it was needed and would be shortened to POO, so I think I will not be changing my name for some time.

Avagoodweekend......
 
The Wayfarer that Sami_Lymington is looking at could be called "Staines"

wayfarer.jpg
 
Hi all,

I am a bit late, but thanks for the advice. Have studied bilge keels and have decided to get to build/convert a larger boat (ex russian 10m?? life boat) with bilge keels and either a lateen or crab claw rig. The hell with performance, will use the first boat mostly with magnetometer survey for wrecks, must sleep 2, have good galley (I am not english so I must eat well) and simple sails and be able to get it on and off a beach with nobody around for 150NM either side.

Regards


Ongolo
 
Cast bilge keels are only fitted as external ballast, normally they are welded steel plate. On a 5m boat this only needs to be 3 - 4mm thickness. A flange is welded to the top of the plate, and through bolted to supports inisde the hull.

Donty skimp on the hull reinforcement, it is amazing the load a bilge plate can exert when it is twisted or the boat grounds sideways in surf for example.

Alternatively, if there is no great depth involved, they can be made of wood, and through bolted.

All pretty straightforward really, as long as adequate support is built in inside.
 
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