Does anyone know how long a boom needs to be when rigged for transom main? 

Thanks, 

Andy

Andy,


I can measure my authentic 50's wooden boom this evening and forward dims. This is geared up for transom.

This boom may have been designed to extend beyond the transom to gain extra leverage on the leach, you won't need that additional length with a modern kicker.

Andy you would want the mainsheet to roughly pull down vertically when close hauled. Therefore just measure from the mast to the transom.

Unless you are going for the full backwards tacking transom sheeting I would stick the mainsheet holes a fair bit away from the transom to avoid it catching under the gunwale at the transom so rather than having a longer boom why not stick the holes for the split sheeting at the right spot.

Hi Andy, just remember it's much easier to chop a bit more off than stick it back on ;-) (top tip)

So how long do I need it then ... ?

i'll measure my boom Andy and let you know. R

I have the same question as Andy / and does the mast length come into it? Mine seems to be 23.5 feet..?

If you are centre-main sheeted then yes as you can have a short foot long luff main or vice versa and don't want the boom much longer than the foot of the sail.  If you have an old boat that is transom sheeted then you may well want the boom quite a bit longer than the foot of the sail so the end of the boom is in the right place for your mainsheet.

Andy, I used the same boom just moved the strops in from the transom, but the length from rear of mast to inside transom 2730mm
Nice to see I have started a trend!

Have fun
Dave F

Thanks Andrew, hog stepped old boat with transom main

Andy

My old wooden 50's jobby measures - 2670mm

R

2730 is for deck stepped

Small query for DaveF please. "Inside edge of transom to deck stepped mast 2730". Fine, but "Deck-Stepping by Dave Fowler" in the library says "to outside edge of transom" is 2730, "and is very critical". So, which is it please? Thanks.

Jacko's measurement for all of his boats was 60 inches from stem to front edge of mast. I measured a number of Canterbury Tales designs and they were all 53 inches from the jib tack to the front of the mast except one which was moved and improved dramatically afterwards.

I think whichever of these measurements you use, they all end up in the same place. I just found it easier to measure from the front because it's shorter.

Presumably, the new boom length needs to be measured horizontally from the mast and a plumb line dropped down to the transom - is the 2730 measured horizontally from the base of the mast, or diagonally from the mast step to the transom top - it may make a few mm of difference?

If you have central sheeting then the black band or even main foot length is the critical measurement if its transom sheeting put the boom on the mast let it drop to the transom and cut it off there it will be about right.

Brain Fade, it was to the outside of the transom measures in a straight line from mast to transom, the boom would need to be a bit longer so you got the pullin from the pullies attached to the end of it.

Thanks DaveF for the clarification. Much appreciated.

Jackos been using transom sheeting since the dinosaurs ruled the earth, why not ask him how long his is (if he says more than six inches watch his nose grow!)