Practical Boat Owner — January 2018

REFINING A RIG

The mainsail that was on

Jenn-Oh when we sailed the

first time was an example of

how low-quality sails can

prematurely spoil a boat’s

performance. It was quite old,

and it was certainly cheaply

made. Not fitting a bolt-rope is

inexcusable.

This sort of thing is a

common problem, especially

on production boats towards

the lower end of the price

range. Builders often supply

budget sails on the basis that

buyers won’t know any better

and wouldn’t be prepared to

pay more for the boat if it

came with a decent suit.

Some builders in particular

have a reputation for skimping

on the sails, and it does them

no favours. If, as is often the

case, the boats are on the

tender side to start with, they

will struggle upwind once the

sails start to stretch.

Excessive heel and leeway

and a heavy helm are classic

symptoms in conditions when

the boat should not be

over-powered or need reefing.

Peter’s sailing experience

always allowed him to get

home, if not as fast as he

would have liked, but anyone

less competent could find

themselves struggling.

If this sounds familiar, have a

good look at your rig and

sails. If the sails can’t be

pulled into a decent shape by

someone with experience of

what to look for, think

seriously about replacements.

Also bear in mind that older

second-hand boats run on a

budget often have cast-off

sails from another type of

boat. There are all sorts of

reasons why they might not

do the job as well as they

should – even if they do

appear to fit the rig. Headsail

sheeting angles are one of the

most common problems, as is

the type and positioning of

deck hardware.

BUDGET SAILS: PROBLEMS AHEAD

PBO VERDICT: What’s the difference?

While beating down the harbour to meet me for our second

sail, Peter found himself out-pointing a slightly larger and much

newer trailable cruiser.

‘All the things we discussed last time seem to be making a

big difference’, he told me. ‘The new main certainly is. There’s

so much more power from it and I’m not getting the weather

helm I used to. It’s still there, but much reduced.’

Something else he has noticed is the ability to make upwind

under mainsail only. It was impossible with the old main.

I saw Jenn-Oh again in last year’s Round the Island Race,

when she performed appreciably better than she had in 2013.

Much remains that could still be done to get the best from

her. I was wondering whether Peter might have adopted my

idea of a mainsheet bridle, but he couldn’t find a way to make it

work and not get in the way with several people aboard.

The standing rigging needs regular checks to make sure it’s

up to tension, otherwise the sag in the forestay will hamper

upwind performance.

And then there’s the headsail.

Although a good deal more

efficient with the new sheeting

arrangement, it’s still past its

prime and, more than likely, not

the right sail anyway.

What matters is that the boat

performs so much better than

she did. A new mainsail and

new standing rigging have been

good investments and the other

mods have been done for the

cost of a few second-hand

blocks and some line.

The mainsail
With a mainsail like she had, it was little
wonder Jenn-Oh had been struggling
upwind: it was more hand-brake than
driving force. As a Dacron sail stretches
with use, not only does it become baggier
but the deepest point (the draft) also
moves aft. A new sail will be cut with its
draft about a third of the way aft from the
luff towards the leech. Once the draft
moves beyond the half-way point as the
cloth stretches – a problem principally
with woven fabrics rather than with
laminates – the sail generates more heel
and weather helm than forward motion. As
the draft in Jenn-Oh’s sail was about
two-thirds of the way aft, she had no
chance. The lightweight sail didn’t even
have a bolt-rope to allow the luff to be
tensioned properly.
On our first outing we pulled what strings
we could to improve matters, but there
was only so much we could do.

Taken on starboard tack because of the

light, this shot of the new main by Kemp

Sails has been flipped for ease of

comparison. Camber stripes allow the

shape to be read much more easily, though

the missing top batten didn’t help

As it was: the mainsail was so hopelessly

stretched that the draft was much closer to

the leech than to the luff...

...and the best that could be done was to

make it marginally less bad. Without

camber stripes (contrasting stripes

running from luff to leech) it’s hard to see

the shape

DIAGRAM 2 If the draft creeps closer to the leech like this, and

can’t be pulled forward (principally by extra luff tension), the sail

has stretched to the point where it’s no longer efficient

DIAGRAM 1 In broad terms, a mainsail’s draft should be between
one-third and half-way back from luff to leech

Draft

Chord

Draft

Chord