T keelson

[tarpeyj]

on my 1960 Thompson sea lancer - the inner T keelson had alot of rot. I removed it but could not completly trace a pattern. How much lower should the outisde boards of the T be from the height of the inside board of the T. If the ribs are 1/2 inch thick, then 1/2 inch lower? This is my first try at repalcing a keel.

[JoeCB]

Those "outside boards" actually support the ribs. Be sure that those boards are tight to the ribs. In the original construction, where the hull was built upside down, the rib ends were first nailed to those "outside boards" to secure location and then drilled and screwed. There is no connection between the rib and the main keelson menber.
Now for the likley bad news... if your keelson is rotted I can almost assure you 100 % that your rib ends are also rotted.

Joe B

[tarpeyj]

thank you Joe, you are right about the rib replacement. so, should the height of the rib after being attached be flush with the height of the inside keel board? That way the bottom plywood lies in contact with everything for fastening.

[JoeCB]

Yes, it sounds like you have it right. The plywood plank that the keel (garboard plank) has to rest flush on the keelson and the ribs. The edge of the keelson that mates to the garboard should have it's surface planed to match the varying angle of the ribs as you move forward from the transom to the stem. When you examin the ends of the original ribs you will notice that they are cut at an angle the does not match the keelson (enter keelson board) ... there is a reason for this. The angle cut creates limber holes allowing bilge water to drain back toward the transom, otherwise it would be trapped between each pair of ribs.

Joe B