Bottom paint on prop
Thanks !
"Bil" wrote in message
...
On Sun, 20 Nov 2005 19:08:32 -0500, "Garland Gray II"
wrote:
"Bil" wrote in
On 20 Nov 2005 08:46:07 -0800, "beaufortnc"
wrote:
Hi,
I'm prepping the bottom of my sailboat for barrier coat then ablative
bottom paint.
I'm thinking, however, that it might be a good idea to paint the prop
with something like Trinidad instead of ablative. It seems to me that
the ablative won't last long on the prop.
What's the conventional wisdom here?
What you use on your prop depends on your pattern of boating. Regular
boat use, eg once or more a week, can mean no special treatment
(depending on your local level of fouling). And on your prop: whether
bronze or stainless steel or plastic etc. And on other characteristics
of your prop, eg whether it's a surface prop, such as a Levi drive; or
a deep prop; whether it's spinning at around 1,000 rpm or two or three
times faster.
If you have a new bronze prop, waxes applied during the polishing
process can mean that no permanent treatment works until that wax is
removed and, perhaps, an etch primer is used.
Some treatments that do work:
* Grease the prop: if you are cruising, but anchor or berth for up to
a month, coating the prop with a salt-water resistant grease works
(for about a month). I use a German-made grease, Bechem SW2, and send
the cook over the side after taking a berth or anchorage. The grease
spins off, taking any slime etc with it. No chance that it can change
the balance of the prop.
* Bagging the prop: a physical barrier, such as a plastic bag, works.
But you have to send the cook (or the cook's assistant) over the side
twice, once to install the bag, once to remove it.
* Painting with an antifouling. Whether you use a hard or ablative
antifouling matters little; the problem is getting the paint to
adhere. New props are a problem, because of the waxes. Older props
work better. And the primer/paint combination is important.
One technique that works is to use an epoxy primer and to follow,
within the prescribed recoating time (usually about an hour, before
the epoxy primer has completely hardened) with antifouling. The next
step is important: then leave to harden completely (ie about one week
- any sooner and the primer will spin off).
I've also used a zinc chromate primer, with some -but not complete -
success.
* Commercially applied silicon coatings. Expensive (applying yourself
is not a good as paying the experts to apply). But works in many
conditions, especially if the boat is used fairly often.
Bil,
This was very informative.
Regarding your suggestion of epoxy primer followed by antifouling, which
expoxy primer do you recommend, and what kind of antifouling ?
I have saildrives with folding props. At last haulout I followed each of
the
many steps (Interlux Primecom as one layer comes to mind) required, but
this
seems simpler.
Thanks.
Garland:
I always beg epoxy primer from the yard which has hauled me out - the
prop does not need much and I usually have no other use for it. So I
take whatever the yard has in terms of left over epoxy primer.
My sailboat is currently wearing International Micron Extran
(International is called Interlux stateside), so that's the antifoul I
use.
To reiterate, the important steps a 1. to apply the antifouling
onto the epoxy primer before the epoxy has dried (usually the
manufacturer will detail the timing on the package); and 2. to leave
the epoxy/antifoul to harden for at least a week.
I have two props, a 2-blade and a 3-blade, so I antifoul whichever is
not on the prop shaft (because I am usually on the hard for only 3
days - and that is not long enough for the primer/antifoul coatings to
harden).
Cheers
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