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Messages - pbyrne

Pages: 1 2 [3] 4 5 ... 18
Main Message Board / Re: Correct engine RPM range
« on: July 22, 2023, 08:29:43 AM »
Ok. Used the laser tach and the following was observed at the slip in neutral.

Tach: 800
Actual: 1000

Full throttle to the stop:
Tach 2500
Actual: 3000

All linkage and stops looked correct and working as expected when moving through motion by my lovely wife and I watched it.

Checked racor and found no water and diesel looked clean to the eye. Have heard that marina is sensitive to fuel quality and there are no reported issues with fuel at marina.

The problem I have is that we didn't see 2500 on the tach but 1600, and the engine didn't sound like it has running full out.

Some local folks have said they have had issues with weeds at the head of the channel that require clearing when boat feels sluggish ...not sure if that was the issue?

All I can say is that at the slip in neutral the engine sounded good.

Main Message Board / Re: Fuel gauge always reads full
« on: July 21, 2023, 06:10:17 AM »
It's a lot of reading and information but do a search for "fuel gage".  Somewhere here is instructions for checking the fuel level sensor I think.  It's a float, lever and rheostat, very low teck.  Hardest part of checking it is emptying cockpit locker. Need a multimeter. Shamrocks was bad when I first got her, bought a generic one from local marine store, has worked for many years.
Honestly, I don't depend on the fuel gage much.  I use the hour meter.  Shamrock usually burns a little less than .7 gallons per hour.  Multiply .7 by hours since last fill up gives me the gallons to fill up.  Find your own burn rate by keeping a log of fuel use divided by engine hours. ie.  gallons per hour or g/h

On the topic of fuel consumption, when you say .7 gph, what RPM are you using?  The Universal Tech manual has double that at @2500 RPM.  Not arguing, just asking.  I realize I need to calc for my boat, but some rough guidelines are always helpful.

Main Message Board / Re: Correct engine RPM range
« on: July 21, 2023, 05:54:07 AM »
My M35B can only get to 2800 rpm (tach reading) before the lever physically hits the binnacle guard.  At 2300-2400, I'm going 7 knots in calm waters.

That's what I remember the boat doing last year.  It's not quite doing either of those numbers, and that's why it feels like something is off.  Other than the tach literally isn't reading more than 1800 full throttle...

Main Message Board / Re: Correct engine RPM range
« on: July 21, 2023, 05:36:52 AM »
If the Tach is off before you trash it exercise the DIP switches or rotary switch setting.  Contacts can become oxidized and produce false readings.  There’s troubleshooting for that in a manual for the gauges.  If you don’t find it on C34 Wiki I can probably find it elsewhere.

This it?

Main Message Board / Re: Correct engine RPM range
« on: July 21, 2023, 05:34:36 AM »
pby : I believe that the tach range for your engine should be  0 to about 2800 rpm (maybe slightly more when not in gear!!)  Idle should be about 1000 rpm so it idles smooth and doesn't rattle you teeth!!

Try Ken's suggestion about cleaning the Tach wire connections at the alternator.  Hard to tell you which colored wires on your alternator??  (mine are the white and the brown wires)

A few thoughts

I'll do that!  I found some photos that might help, but I don't see any wires in them, so maybe not very useful.

Main Message Board / Re: Fuel gauge always reads full
« on: July 19, 2023, 08:39:18 PM »
I replaced mine with a reed switch type sending unit from Catalina Direct. PN Z3529.

Yeah.  That's the part from CD '

that I think is a direct match for this:|10273&product=75153522&code=739729000038

Main Message Board / Re: Fuel gauge always reads full
« on: July 19, 2023, 08:36:49 PM »
No one knows what tank you have except you! Lots of changes possible, often varying boat to boat. Take off the bulkhead and measure the height of tank. Or even better, remove the sender and measure it.

True.  The boat is 2 hours away and I have to order it.  I've only got a limited time this weekend to fix it, so I'm willing to make an educated guess as to the size so I can work on it this weekend.

I found some photos that are not perfect, but they do show the size of the tank.  It seems to fill the space, and I think it's supposed to be 25 gallons.

Main Message Board / Re: Fuel gauge always reads full
« on: July 19, 2023, 02:35:09 PM »
I'm not at the boat to check, but would the 12" sender listed here but the correct replacement?|10273&product=75153522&code=739729000038

Main Message Board / Re: Correct engine RPM range
« on: July 19, 2023, 12:47:13 PM »
No clue, I am not a mechanic. Others may respond with more helpful info. However, if your boat goes 6+ knots (confirmed by GPS in slack water) with tach reading 1600, I suspect your tach is reading incorrectly.

LOL. Fair enough.

Something else that came to mind is that the boat was just moved to a marina where we used the marina's fuel.  Prior to that it was jerry can fed from Shell Gas Pumps.  I'm thinking maybe I should consider the possibility the filters need changed.

Previously, they were changed infrequently from what I can tell.  It was on my list for fall maintenance with the oil change for winterization.... but maybe it needs to be done now?  Seems wierd that a top up ONCE would cause an issue with filters though...

Main Message Board / Re: barrier coat/ bottom paint / VC17
« on: July 19, 2023, 12:09:30 PM »

In Lake Michigan I've gone two seasons without repainting with no ill effects.  Will you be returning to Michigan after your trip and how long and where will you be in salt water? 

VC-17 isn't compatible with any other paints (see so I'd select  paint based on where the boat will spend most of its time.


That's why I keep using it.  If I had a chance to go with something else, without having to clean the hull to the gel coat I would.   Your choice of course, however I don't find the benefits of VC17 to be worth having to redo it with what looks like copper but is priced like gold...

Maybe have a look at this thread?  I posted my setup in this link:,11730.msg94988.html#msg94988

Main Message Board / Re: Correct engine RPM range
« on: July 19, 2023, 12:06:18 PM »
It is easier to have a helper when checking tach with laser. One person on laser and one in cockpit at throttle. Run though idle to full throttle (in neutral)—communicating with each other, and charting the results every 100 RPMs or so— comparing actual (laser) to tach readings. Error rate/difference may vary and not be constant throughout the range. You may want to just make a deviation chart and use/memorize /refer to it instead of trying a adjust out the tach error.

Got it.

Anything else I can focus on?  If I find the RPM's are too low on the engine then what?

Main Message Board / Re: Correct engine RPM range
« on: July 19, 2023, 06:28:14 AM »
Ok. Laser Tach on order.

Reading this thread, I will say that nothing has been done to the engine,11302.msg90447.html#msg90447

Oil changed last year, fresh fuel, starts immediately, and hasn't missed a beat the couple of times we had her out. In fact you can hear it here:,11687.0.html

For completeness what/how should I be verifying the linkage, cables etc, to make sure I've inspected everything.  The engine sounds fine to me other than it's not rev'ing as high as I think it should; by sound anyways.

At the moment I'm going to:
1) check RPM at idle in slip
2) check RPM with Laser Tach
3) Alternator (which I'm not sure how to do)

I'm 2 hours away from the boat, so I have to check everything when I'm there.

Main Message Board / Re: Folding or feathering propeller
« on: July 18, 2023, 09:39:40 PM »
I have a variprop 3 blade.  I'm uncertain of the pitch, as it came with the boat.

But, I can say it provides good thrust, never is an issue going between forward and reverse, and it's very well made.  It's a lovely piece of engineering.  It probably the only thing on the boat I actually look forward to servicing!  No idea why...

It does need to be greased seasonally though.

Main Message Board / Re: Solar vs. Alternator Upgrade vs. ???
« on: July 18, 2023, 09:31:50 PM »
pby : Th equalize the temperature difference between the top and the bottom of the fridge box here what I do:

I purchased a "Fridge Mate" - it's a "D" battery small fan.  I tied a line on it so it loops around the Temp control and is pointed slightly down.  It really works, out of the way and the battery lasts for MANY hours.  After a trip you just pop out the battery and it's ready to go for the next time!!

A thought

That's a great idea! 

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