Yachting

LETTERS

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10 http://www.yachtingmonthly.com MAY 2016

Calibration counts

Tom Partridge’s How to use Satellite Images

for Navigation (Mar 16) makes very interesting

reading. Without doubt, satellite-based

navigation makes our work simpler and more

accurate, but I’m glad he draws attention to

the potential and actual problems involved.

The National Geographic TV series Air Crash

Investigation is based on published reports

of formal investigations, with excellent visual

material and interviews with survivors and

experts. Of particular interest to cruisers are

the repeated incidences of over reliance on

automated navigation systems. These can

and do fail, with disastrous consequences.

Instances include incorrect positioning due to

setup error, failure of feeder systems including

speed, pitch and altitude, even compass

errors. These can be aggravated by the cockpit

crew failing to accept that the systems can fail,

despite what they can physically see.

Well trained as we may well be, we could

fall foul of similar problems. Maybe the log

is misreading, the depth sounder incorrectly

calibrated, the wind indicator sticking. If

all of these are feeding our navigation and

pilotage system we could make a serious error,

hopefully with less disastrous results.

Garry Flashman

With electronic

navigation, error

in means error

out. Always

doublecheck

with the Mk

eyeball

Photo: SuSie Plume

Ultrasonic antifoul

correction

Your article What happens when they ban

antifoul? (Feb 16) contains a glaring error in a

photo caption that reads: ‘Ultrasonic antifoul

systems repel barnacles, but not weed and

slime.’ How wrong can you be? Ultrasonic

antifouling is a bio-deterrent system that

primarily targets the bacteria (microscopic

cells) that form bio-films – otherwise known

as slime – in addition to algae cells.

Nick Griffin, Ultrasonic Antifouling Ltd

Surreal soggy dollar

Chris’s article about the British Virgin Islands

brought back some happy flotilla memories.

We spent a surreal New Year’s Eve at the

Soggy Dollar Bar, ending up on a superyacht

with a well-known Formula 1 boss.

When he asked his crew go ashore to

find some party people, I don’t think that

three middle-aged parents and their giddy

teenagers were what he had in mind! But he

was charming and spent the night introducing

us to Jägerbombs! Waking up the next day in

the bunk of our humble 34ft Sunsail yacht,

I wasn’t sure if it had happened at all.

Andy Robinson

Use halyard and

prusik loop

The response to my letter

of the month (Nov 15)

confirms that we

don’t need rocket

science to solve

the problem

of keeping

yachties in the

yacht. The use

of a topping lift

or spare halyard

is promising and

I propose this

solution to the

problem of taking

up slack when going forward.

Make a Prusik loop with about 1.5m of

5-6mm line using a double fisherman’s

knot and cow-hitch the loop to a carabiner

close to the knot. When going forward,

attach the end of the topping lift to the

lifejacket harness, then tie the Prusik loop

to the topping lift with a Prusik knot and

clip the carabiner to the harness. When

going forward, slide the Prusik knot up

the topping lift to take up the slack, which

will hang in a loop from the harness; when

returning aft, slide the knot back down.

The only refinement I would add before

going forward is to tie a figure-of-eight in

the topping lift behind the clutch, in case

someone should accidentally release it.

Professor Paul Rodhouse

A Prusik loop solves

the problem of taking

up slack if going

forward using a halyard

instead of a jackstay

Use halyard and jackstay

Regarding my letter on halyard tethering in

lieu of jackstays (Feb 16), I favour this for the

reasons stated, but it would be better for the

halyard to be clipped onto a full body safety

harness than a lifejacket’s chest harness as this

will distribute the body’s weight better.

Also, the halyard should he clipped onto the

front as opposed to the back of the harness, as

this allows the wearer to regain control more

easily. Using this with a conventional tether on

a jackstay would also reduce the risk of being

swung on the halyard if thrown by heavy seas.

Tony Hughes

Photo: AlAmy

Photo: ChriS BeeSon

The Soggy Dollar Bar, on White Bay in Jost

Van Dyke, BVI, has seen some crazy evenings

Just suck it up! Vacuum-

bag your rubbish

While sailing in the ARC+ rally in Hejira, our

Southerly 135 we had to address the problem

of accumulated rubbish, mainly plastic food

packaging. This can be bulky and inevitably

becomes smelly in the warm conditions.

We came up with a novel solution to both

seal and compact the refuse so that it could

be stored flat in the bilge pending disposal in

the Caribbean. We used a homemade adaptor

on a rechargeable vacuum cleaner and cheap

vacuum storage bags. Simple!

Nick Mines

ItÕs a tidy way to avoid the problem of a

locker full of reeking rubbish

Photo: niCk mineS