I have a 2" carbon tube that can be a nice boom. F17 main and mast (once repaired).

What do I need to build it right?

I have an TheMightyHobie18 boom janging in the garage for parts.

gooseneck, some kind of outhaul setup, fitting/loop for mainsheet. Anything else?

details appreciated.
thanks.

Gooseneck.

Try and find a fitting that has a male part attached to the mast and then a socket in the boom. Lay up a composite socket (wrap the gooseneck fitting in tape and use it as the mould and then bond it into the end of the boom.

Outhaul.

Cut a "V" groove in the back end off the boom. depending on thewall thickness of the tube you might want to build it up a bit. Tie a line onto the clue and put a couple of knots in the rpoe to put in the groove.

As you said a webbing loop for the clew.

Job done.

I once used a bent stainless 316 plate and a stay terminal as a gooseneck. Worked very well!

A square hunk of delrin, about 2" long, and half the diameter of the inside of the boom, bolt the delrin into the boom and drill a hole in the delrin to accept a bolt on the mast.

Delrin's pretty durable, easy to shape with a knife.

Good stuff. thanks!

So, depending on how you rig the clew attachment, you might need a beefier gooseneck than have been suggested here so far. If you've got the clew attached to the boom, with the mainsheet attached at a different location, say near the boom end, then boom will experience a lot of compression loading when the main is sheeted hard. You'll need a sturdy gooseneck to handle it. Might be wise to adapt an exisitng gooseneck to work on your boom section. Here is an example of this setup:


As the main attachment is placed further aft, compression loading increases as the blocks/sheet angle to the rear beam goes well past vertical. You need some angle to get reasonable mast rotation.


If you use a webbing strap around the boom, with the clew attached above and the main blocks attached below to the same strap you can minimize the compression loading, but might loose mast rotation stability, esp. in lighter air.

Here's an example:

If the clew and main are on the same strap, the outhaul then pulls both back? Is that any benefit?

THIS ... is my BOOOOOOM!!(stick)

Sorry, I just had to.

Shop smart, shop S-Mart!!

Bruce Da Man!

noo my pic went byebye.

If on the same strap, then you will increase the sheeting angle as you apply more outhaul...which is loosely tied to how much wind you have...more wind more outhaul. So, having more sheet angle in more wind is not a problem and can help with mast rotation in certain conditions (choppy in light to moderate winds are where you get lots of rotator slap). But when you are inlight stuff, and you apply less outhaul, your sheet angle will also be less or nearly vertical, so you're mast flopping will not be prevented.

On the photos I showed above with the outhaul's external to the boom, there are no methods for actually pulling the clew forward when the outhaul is eased. Nearly all boats I've sailed have the outhaul control lines internal to the boom with a small traveller car or plate the the clew attaches to. There is also a line or cable attached to a large diameter bungie (all in side the boom) that provides in-haul when the outhaul line is eased. Not sure how much the webbing or lashing straps shown in the picture will actually move when the outhaul is eased.

Don't over design the outhaul too much. I rarely touch it as it is not easily reachable when going around buoys. But pulling the downhaul also pulls in the foot of the sail. One control, two usages...

When flying a chute down wind, is there a need to use outhaul at all? The main is acting as the stay, traveler near center, can we minimize the importance of outhaul except in the lightest air?

Definately, particularly because as mentioned above the cuningham effects the foot tension anyway, so dumping cunno at the top mark also softens the foot. Thats why I suggested a simple knot and groove outhaul system.

In light air, playing your outhaul can help tons.