It's easy to improvise a cheap boom for a Hobie kayak or Island sail. Here's how:
1. Buy some collapsing fibreglass fishing rod blanks of the diameter/stiffness you want (I used a 5 m and a 6 m rod for my Adventure Island boom) 2. Assemble your chosen sections, twisting and pulling or pushing hard to stop the sections from collapsing in use
3. Wrap a 1m length of padded self-adhesive bandage around the mast end of the boom to stop it chafing on the mast when the boom is on the windward side. I used extra adhsive bandage on top of that and at the other end of the boom too.
4. Attach the boom to the mast with a prusik loop (I use 3 turns and a fairly tight loop, but not so tight that the mast can't rotate freely) 5. Attach the clew eye of the sail to the other end of the boom with another prusick loop, then the mainsheet pulley hook to the boom with a third prusick loop on the INSIDE of the prussic loop for the clew eye - I used 2 turns for both these loops
The advantage of such a boom over a boombat or no boom at all is that you can control/adjust the sail draft for any sail angle by heading into the wind to take the tension off the sail, then reaching up and back to slide the clew and mainsheet pulley prussic loops along the boom. Prusik loops are wonderful in that they slide easily unless under tension, when they lock up completely - this means you can still furl the sail by sliding the aftmost loops along the boom as you furl the sail.
One disadvantage of such a boom compared to a boombat is that the boom, being straight, is lower, so that you need to lean back more to go under it when tacking or jibing.
My boom works well downwind in less than 10 knot winds as it stops the sail from collapsing, but becuase there'd no vang the boom does lift in stronger gusts, making it harder to control the sail than when I use my (smaller) aftermarket sail with boom and vang.
It's hard to fit an effective vang (from the mast base to the boom) because the Hobie sails go down to almost deck level, meaning that the angle between the vang and the boom is very small, resulting in poor mechanical advantage (although there is someone on this forum who has done this)
