Educate me on the use of the sail's telltales

[Babylon]

Your backstay is the primary control of leech tension on your mainsail, so I'd use that before using the cunninham on the main.

What if one has fixed backstays and no Cunningham? That leaves halyard, kicker, mainsheet and traveller (and of course clew outhaul).

Boat is a heavy, long-keel Vancouver 27 with a cutter rig, but I still try to trim for optimum performance.

Weaknesses are we don't point very high and we get stopped by short seas especially in poor winds, so drive and sustainable pointing to windward is my holy grail.

Also find the forward 1/3 of the main gets backwinded by the stays'l - if I do anything to reduce the backwinding, we lose speed!

 

[Javelin]

Your backstay is the primary control of leech tension on your mainsail, so I'd use that before using the cunningham on the main.

This relates to a fractional rig and not to a Masthead rig.
Masthead rig controls are quite different.

Pointing is relative, so "we don't point very well" really only means anything if comparing like for like boats and rigs.
I note you sail in the Solent and the Solent short chop is horrible for boats under 35' in my experience.

To get through it, especially with a heavy displacement hull you need grunt.
So this usually means full sails as opposed to flat fast ones.
Plenty of twist which will give acceleration after being bounced by a nasty chop.

I've sailed big cutter rigged boats - 45 to 55 but not had the opportunity to sail a 27' one but I guess the same rules apply.

The hull form, high clews on the jibs and relatively small main don't make for great upwind sailing anyway.
There is a lot going on in the slot area with the staysail and yankee so getting backwinding is not much of a surprise.
My comments about main halyard tension still applies though so watch you don't pull too much luff tension on.
Do not over tension your clew out haul. If you need pore power I'd try easing it off a bit.

Apart from that I think you need to become a master of VMG.
My bet is that cracking off just a little bit will actually give you better overall upwind speed than trying to point.
It will certainly help with power to get through the chop and the extra distance sailed will be made up with a higher average speed.

 

[Babylon]

This relates to a fractional rig and not to a Masthead rig.
Masthead rig controls are quite different.

Pointing is relative, so "we don't point very well" really only means anything if comparing like for like boats and rigs.
I note you sail in the Solent and the Solent short chop is horrible for boats under 35' in my experience.

To get through it, especially with a heavy displacement hull you need grunt.
So this usually means full sails as opposed to flat fast ones.
Plenty of twist which will give acceleration after being bounced by a nasty chop.

I've sailed big cutter rigged boats - 45 to 55 but not had the opportunity to sail a 27' one but I guess the same rules apply.

The hull form, high clews on the jibs and relatively small main don't make for great upwind sailing anyway.
There is a lot going on in the slot area with the staysail and yankee so getting backwinding is not much of a surprise.
My comments about main halyard tension still applies though so watch you don't pull too much luff tension on.
Do not over tension your clew out haul. If you need pore power I'd try easing it off a bit.

Apart from that I think you need to become a master of VMG.
My bet is that cracking off just a little bit will actually give you better overall upwind speed than trying to point.
It will certainly help with power to get through the chop and the extra distance sailed will be made up with a higher average speed.

Goodness me! You've described exactly what I do! The only time I crack on the halyard and clew outhaul tension is in flatter water with stiffer winds, in which case I also drop the mainsheet down the traveller to flatten the sail - but this takes more concentration on the helm to hold her in the groove. (The windvane in more open water works a treat however. )

Of course, there's more tweaking with two headsails, but the principle of trimming the foreward most sail first and progressing aft applies whatever rig.

Thanks for the excellent advice throughout this thread.