New engine panel and wire harness - question on in-line fuse

[Lennysails]

My 1989 C34 (M-25 XP) Naughty Hall got a critical upgrade today.  I can't find the forum comments on adding an in-line fuse close to the helm engine panel.  Any help to that location or comments would be great.  BTW, I called CD yesterday and they had nothing on the electric fuel pump being directly connected to the key switch.  Found the info on this forum 
Thanks Lenny

[KWKloeber]

[Edited]

Lenny ...

[Caveat - this is for the Non "A" and Non "B" engines, in other words for the M-25, XP (NOT XPA or XPA(C) (and same thing for the M-35 series.)

First, you may have noticed that the fuel pump power (typically red) and alternator field excite wire (purple) are redundant - they both originate at the key switch "I" terminal.   When redoing harnesses I use one 14 awg wire (16 awg is plenty) and split it at the engine compartment.  Actually I make up a custom plug that connects to the alt field, then a plug back to the fuel pump, and that way either could be disconnected/serviced separately.  But it is a-ok to just put a splice on the wire somewhere in the engine compartment.  Like run it to the pump area, and splice off to the Facet and alt.

To your comment: You also won't find anything about the fuel-gauge sender (pink) wire on the schematics, etc., because they weren't "Universal" they were "Catalina" installed.  Many times you also won't see the tach-signal wire on schematics.

Re: CD, what comes to mind is "Not all that."  Members in states south of the M-D Line know the euphemism well. Witness: you won't find anything about properly fusing their "harness" which isn't a harness, it's an overpriced hunk of wire.  Or that the instructions on doing the harness gummy bear Mod doesn't comply with ABYC.  Yet they get away with it because owners who don't know better get sucked in.

To your question:
There's two issues Re: harness/panel overcurrent protection.

1st - Fusing the feed TO THE panel within 7" (per ABYC) of the power source (the starter solenoid "B" post.)
So if the harness shorts you don't burn up the boat.  I typically use a 30-a fuse (but newer glow plug can pull close to 10a so sometimes it needs a larger fuse.)

2nd - Protecting the lighter than 10 awg wire IN THE the panel and those coming BACK TO the engine.

If you have a 30-a fuse TO THE panel, then by AYBC there *must* be a lighter fuse (sized per the panel wiring (typically 16 awg to the gauges,) etc.) 
It's all low amp so a 10-a fuse is fine.  What I have done when refurbing panels, is put a blue sea pushbutton breaker w/ weathertight cap on the panel.  Everything fed by the key switch (except 10-ga wires like glow plugs) is run thru that breaker so that it protects everything beyond the key.  The fatter wiring is protected by the fuse at the solenoid,  The panel breaker protects the following wiring:

     * Power from the key switch to & lights on the gauges.
     * Blower motor (hmmmm. red maybe brown?)
     * Alt-field-excite wire (purple.)
     * Fuel pump wire (red.)
     * Solenoid "S", start wire (yel/red stripe.)

The low-oil-pressure switch (blue,) fuel gauge (pink,) temp gauge sender (tan or brown) and hi-temp switch (tan or brown) are irrelevant -- as I said they go to ground and can't be shorted/burnt-up but they are still protected cuz they are powered thru the gauges (so they are protected by the breaker.)  Likewise the tach signal TO the panel doesn't NEED to be fused, but it doesn't hurt if you do.

If one has a 12-volt power outlet at the panel, then that needs to be considered in the fusing/breaker scheme.

You may have seen this: (To understand more about HOW the harness functions - actually if you know that you'll know the answer to your question.  But regardless it's good to know it in case you need to troubleshoot anything down the road.)
https://c34.org/bbs/index.php/topic,8385.msg59165.html#msg59165

For the panel power feed, I use a tinned, 10-awg, ATC, weather-capped fuseholder (tricky to find) at the solenoid (it's an M8 post, so uses a 5/16" terminal.  BUT I WILL NEVER EVER use a 10 awg x 5/16" ring terminal.  They are simply (IMO) WAY WAY WAY too flimsy (for a harness wire where there's movement and vibration.)  I use an M8 starter lug (hefty and will NOT bend and twist or break off.)  But they require a special heavy crimper.  (I also will not use ring terminals for Alt post connections (AO and negative).)  If you want to, PM me your address and I'll throw one in the mail.

Did you use the same type quick-disconnect as on the OEM harness solenoid "S" wire (I call it a quick heat-up, corrode, loosen, and fall-off terminal)? That type does not belong on a boat, especially in a critical location (starting?) and in the engine compartment (heat, moisture corrosion.). You might want to change that.  See here:
https://groups.io/g/Catalina30/wiki/7401

https://groups.io/g/Catalina30/wiki/11336


-ken

Thats my story and I'm sticking to it.

[Ron Hill]

Lenny : I don't recall any posts on a fuse for the positive wire close to the engine panel.  Not too sure of the size amperage - 10Amp? 
Do you have the glow plug solenoid modification?  If you don't that may dictate the size fuse.

I'd hard wire the panel wires into the harness, as you'll probably never completely remove your engine panel again.

If you do install one I'd suggest that you use a "stab-in" type inline fuse and holder, rather than the "Buss" cylindrical glass type fuse.  In the Buss holder the spring tends to loose contact over time - anyway that's my experience with them!

A few thoughts