Posted: April 10 2012 at 08:58 | IP Logged

Hi All,

I'm new to the forum and to Thompson.  I picked up a 1990 Thompson Adventurer 288 earlier this year.  In going through the boat to fix a bunch of minor issues,  I found all of the original paperwork and a set of blue prints for the electrical system in a storage bin!  I know some of you were looking for a set, although it's been a few years since anything was posted about that.  I have access to a large format scanner so if anyone needs a PDF let me know.

My boat had a strange set of problems.  It would not start up on either engine unless bot battery banks were on.  Also it would not charge properly (according to the gauges).  The mechanic who inspected the boat for the seller indicated both gauges needed to be replaced.  The clue to me was that with one battery bank turned on,  the respective engine and gauges would power up and when you turned the key to crank,  the solenoid would click but the starter wouldn't turn.  With both battery banks on it would fire right up.  Also the boat had brand new but dead batteries on it. 

After much studying the schematics I figured out that the factory ran the main +12V wiring to the wrong engines.  All of the gauges for the port engine have a stripe while the starboard wiring does not.  I traced the main +12V wiring and found it also has a stripe at the port keyswitch fuse connection,  but it runs to the opposite engine harness!  Factory mistake.  I reversed the wiring at the key switch fuses and everything works perfect now.  No more charging issues and each engine will start solely with its respective battery bank on.

There have been plenty of other issues,  some factory and mostly shoddy mechanic work over the years.  For example,  the boat has Monitor FWC systems on it.  Someone installed 140 deg thermostats!  Ouch that is cold and not so great for the engines.  I found out why they did later on.  When I put in the correct 160 deg thermostats,  I discovered each engine had TWO thermostats.  Someone left the original 'stock' intake thermostats in plus the ones that go in the Monitor manifold.  Monitor tech support confirmed this is a big no-no.  Now each engine has a single 160 in it and works great.

When shutting down the engines,  or for that matter when cruising for an hour or two,  the cabin of the boat would get very warm, stuffy,  engine smelling inside that drove my wife crazy.  Now we know why they ran 140's.  The head in particular would get very hot with the heat coming through the mirror that is also access to the wiring.  I planned to put a foam seal on the mirror until.....

Shocked to see a 12,000 btu reverse cycle AC system with only a single 4 X 8 vent in the middle of the boat,  I started planning a duct and extra vent or two.  While figuring out the best place to locate everything, I realized the engine bay was completely open to the cabin via a space behind the head and galley.  There is a gap around 2" X 8" that opens into the area behind the galley cabinets!! WTH?  So I completely sealed that off by building in a piece of that foil lined fiberglass board used for building HVAC ducts.  I added in a vent on the side wall below the 'captains cabinet' and T'd that into the new sealed off area.  Now cold AC air feeds into the space behind the head and galley.  500% improvement to the boat and no more heat during/after engine operation.

Ooops my post is getting too long!  Anyway I hope there are still some other Thompson owners lurking.