T&T: impeller change

[Larry N. Brown]

Couple years ago on the list, I heard about quick change impeller cover kits.
They didn't have one for my mains nor genset. Got several good ideas.

Troubleshooting an airconditioner problem while anchored out behind an island
on the n. gulf coast, I smoked a genset impeller. Forgot to open seacock.
Duh.

Not to panic. Located spare and seal. My replacement for the quick-seal kit
consisted of replacing the fiddly little straight slot screws with hex head
machine screws. Though still rather small, they have a knurled head that a
pair of thick fingers can still get purchase on. So, remove plate, seal and
damaged impeller. Replace same. Then-- the magic-- loosely install two studs
one on each side of the pump face. Gasket and plate slip on easily and are
held in position as the hex screws are installed. Remove studs to a special
zippie and install the last 2 hex screws. Tighten all down snugly. Le Voila;
15 minute impeller change. No cussing.

Lessons learned. Make this change NOW. I had to order boxes of 50 hex screws,
one for mains and one for genset. Make the studs now as well. If you have a
Yanmar main or Kohler(yanmar powered but different machine screw) genset, let
me know and I'll send the screws- I have about 40 of each left.

The only reason i could readily find the impeller is I saw it while looking
for something else the other day. No, no, no. In a dedicated zippie, in a
dedicated place, have a couple more impellers and seals, and the box of hex
screws just in case and a dedicated hex head driver. Cheap insurance that
saved my bacon. Emerging from that engine room to 100d patio deck air was a
blessing.

Mark pump and face plate so it's a snap to replace gasket and plate without
having to think about it.

Come up with a foolproof way to keep from cranking machinery with through hull
closed. Get a flow sensor to warn on no flow. Come up with some kind of inline
basket to trap impeller blades and pieces and install it in an easily
accessible place.

The main engine and seachest intakes are seacocks with clam shell shaped
grates to keep out big stuff- twigs, plastic bags. Down side is that it can be
more easily blocked by trapped marine life and is not easily cleanable by a
free dive. Scuba? El no sweat-o. Pull the plate screws and bring up the grate
to wire brush on deck. Clean the outside of the TH and the interior with a
wire brush and a wire bottle brush. Reassemble. MAKE THIS A ROUTINE.
Preventive maintenance.

I have no marine growth problem with the main strainers. Very quickly, any
marine life dies due to O2 deprivation and I never see growth in the
strainers. Genset shares strainer with AC's which run frequently if not
constantly in summer. So. I'm installing an auxilliary 1 1/2" through hull and
valve. Not a sea cock. No clamshell. Pull the hose, open the valve and clear
the sucker out with a broom handle. Located in an easily accessible place in a
different part of the hull. Plumb it to the ER with PVC and construct a PVC
manifold. Idea is to normally run the AC's and washdown pump off this rw
supply and the seachest with genset and watermaker rw should stay as clean as
the main strainers.

Ordinarily, the aux strainer will see AC and seawater washdown flow. Strainer
and TH are easily serviced and they can also serve as alternate flow for a
main or the seachest in case of problems.

Oh, and I'm gonna install it with Cigano in the water.

Now, since I'm cruising and no longer building a boat, I can work on
improvements at a more leisurely pace. Sit on the patio deck with something
cool and a fat seegar and think my life away. Thinking about plumbing the AC
RW circuits in mostly 3/4" PVC and install a washing manifold. Loop so I can
dump in and circulate soapy water while the AC is turned off. Reset manifuld,
flush and go. Positive switch instead of using the AC relay while washing. I'd
love to use PEX but the connectors/adapters are all brass. Any one know of SS
or bronze PEX fittings?

I'd like to wire in the flow sensor to shut down the genset and warn about the
mains and I'd appreciate any ideas regardless of how far out they may be.

All's well aboard Cigano on the MS gulf coast with a jaundiced eye on the ITCZ
and tropical waves.

Regards

Larry
M/V Cigano
47' Prairie Sundeck Cruiser
Lying Bay St. Louis, MS