mast angle

[Killick69]

Hey all, does anyone know correct angle to set mast to? I would think it rakes to the stern (leans back) and that there is no bend. Guess one sets it up with the lower shrouds and then one tensions upper shrouds (being careful not to induce bend). It is going to be interesting, as Fenwicks (I used their crane to remove mast) have sold crane and all my mates are keen for us to step the mast, using ropes with the boat tied to pubic jetty. Let's hear what you all think. Cheers, John.

[SeaLady]

Can we film it?

Sorry but stepping your own mast with a bunch of blokes could make interesting viewing.

May need it rated R for occasional coarse language.

[storm petrel]

G'day John,

I have a copy of Formit Fibreglass' sail plan for the Mk2. It states that mast rake should be between 0 and 200mm (zero and 8" in the old money).

Adding mast rake adds weather helm and as Tophats seem to have quite a bit already I would tend to rig the stick vertically first then go for a sail in a moderate breeze(about 12-15knots). If you have a little weather helm in this strength breeze, leave the mast vertical but if you have no weather helm or if you find you have lee helm(unlikely with a Tophat) get the spanner out and rake the mast back a bit.

A little mast bend is OK (mast bend tends to flatten the main) and is probably unavoidable with correctly tensioned forward lowers and backstay.

If you can borrow a Loo's rig tension gauge(or similar) when you are tensioning the rig it will make the job a lot easier and ensure you have balanced the tension on each side and have the tension in the uppers and lowers (for and aft) adjusted correctly. I have a gauge you can borrow but I live on the Central Coast. I am sure Fenwicks would have one.

Good Luck,
Mark
'Storm Petrel'

[Killick69]

HI Diana and Mark,
Sure you may film the event. It's gotta be a laugh.
Mark, that is useful info. I guess I will aim at vertical or close to vertical, in which case I can use a spirit level. I will aim at zero to 50 mm rearward rake, so 5 mm spacer placed at one end of spirit level will mean 50mm rake when spirit level shows vertical (mast is about 9.5mm and spirit level is about 1 metre long). Am thinking of putting a square (large) on the track on coachhouse roof and using it to check that mast is in alignment Port to Starboard. Mark, do you know what the tension should be and is it the same on all stays? Cheers, John

[storm petrel]

Hi John,

I just hang a heavy weight from the main halyard to check the rake of the mast(stand in the middle of the boat when you do this and keep others off the boat). You can also use the main halyard to ensure the mast is not leaning sideways by using the halyard to measure the distance from the top of the mast to a point on the port and starboard gunwales(the points should be the same distance from the bow on both sides) .

On my boat (3/16th wire) I have found from tuning while sailing that the tensions that work best are:
350-400kg on the backstay
250-260kg on the uppers and forward lowers
160-180kg on the aft lowers

Rule of thumb is:
Backstay about 15% of breaking strain
Shrouds about 10-12% of breaking strain.

Cheers,
Mark

[Tales]

John,

Mark is pretty spot on from my experience on Tales.

We run about 100mm mast rake.

Not sure about flattening the main by bending the mast though. That will only work if the sail was cut for a bent mast. Should be flattest on a TH with the mast straight.

Cheers,

Tom

[Killick69]

Thanks, that is the info I was after.
Cheers, John