More Tomcat observations/chat

thataway":2y0xsmuv said:
I have to also correct for the engine being offset, It is only a little more than 1/8 turn, but there is definate pressure, and the boat would do circles if I didn't correct.The twin screw trawler I owned had to have rudder correction when running on one engine.

Matt, Did you say that you got on a plane with a single engine? That is just not possiable with my boat. I think I have tried all combinations of trim.--maybe I didn't trim the bow up enough--I'll have to try that.

What was your RPM Vs speed on a single?

I cannot get max RPM with the single engine. I do have lower pitched props and I could try that to see if it would plane the boat---however, I believe that it would be severely lugging the engine.

Since we are all farily close at planing speeds, I suspect that the lower speeds have to do with loading, attitude of the boat, and the accuracy of the flow meters. I did one fill up to fill up (about 200 miles), mostly at 7 knots and my flow seemed within 5%. But as you go lower, it will be less accurate.
Click to expand...

I was able to get fully planed off with one engine. I ran the engine up to 3000rpm planed off as I recall and backed off from there. I did not check my speed for that test. I made a small correction to starboard, but it was not a significant as was expected based on what I read from others here. I was loaded light, just me aboard, no significant gear, perhaps 1/4 fuel tanks. I trimmed my port engine out of the water and ran with just my starboard engine.
 
There has to be a large difference in weight--I did still have a little of the lower unit (the prop was on the surface--but not the nose of the gear case out of the water) in the water. The reason I didn't pull the motor all of the way up, was that I was under the impression that steering with the engine all of the way up, put undue loads on the steering ram because of the geometry.

In my case, the max RPM I could get with the single engine was 3000, at 7.5 knots and 8.2 gallons per hour. My boat starts to plane at about 11 knots.
With both engines, I get to this speed with about 2600 RPM, but if I drop back it comes off a plane rapidly. At 2500 I am back down to 7.8 knots.

I even tried planing with a single engine when the boat was new, and as I recollect I could not--but did not have the Permatrims at that time.
 
OK,
I went down to the nearest fuel dock (14 miles) to tank up just in case we had to move or pull out with the storms coming our way... Good time to experiment with planing on one engine. No matter what I did, I could not get the boat over 7 knots on one engine--and max RPM was 3200. This included pulling the lazy motor all of the way out of the water. Then I put the boat on a fast plan, and cut one motor, pulling it out of the water as fast as I could. The boat came off the plane, and stayed at 7 knots max.

Matt, I would love to see some RPM and GPS speeds on your boat on a plane on a single engine. I have to estimate that at that time I had about 500 lbs extra gear aboard--includes 25% fuel, microwave, generator, 3.5 hp outboard, Air conditioning, tools, and empty freezer--no water,

Interesting, but the fuel dock sold zero fuel since last Thursday (before labor day). The hurricane scared people to the point that they just didn't use their boats--and many put the boats up in hurricane holes, even though the storm was never predicted to get to our area--or at least we were on the very outer cone. My favorite Nordhavn 62 was back in her slip--with mud dripping off the 100 lb CQR and 120 lb Bruce...had been up one of the bayous.
 
thataway":1ip0miur said:
....
Matt, I would love to see some RPM and GPS speeds on your boat on a plane on a single engine. ...
Click to expand...

Hi Bob.
I found my original post when I tested the single engine and everything was fresh in my mind. I will paste it below:

>>Well today I decided to finally test running my Tomcat with one engine.

I shut off my port engine and trimmed it completely out of the water. Using just my starboard engine I ran it up. The engine definitely lugs, but she was able to plane off. My engine got up to 4000 rpm but I backed it down after that. I'm assuming it would go higher with enough time but I just wanted to see if I could plane off on one engine. I was not exactly light today either...3/4 tanks of fuel, 150 pounds of dive gear, etc. It took a while to get planed off, and of course it was slow to accelerate over plane but it was steady and got the job done. As you can imagine with one engine up the steering is stiff but manageable. I'm impressed and pleased to know I can plane with one engine if necessary. I did not notice any unusual handling characteristics other than the slow plane time of course and the stiffer steering.<<

Next time out I will check my speed when I'm planed off.
 
***

Lady KC might have had her last major run of the season,
going to and from River Dunes Marina, Broad Creek, NC
from our slip up the Neuse River at New Bern/Bridgeton, NC.

With 3/4 tank of fuel and 1/2 tank of water,
and with the Honda 135's in the full down position,
the GPS said we did about 80 miles averaging 17.5mph.

It seems like each engine used approximately
5 gal per hr.
or we went 4 miles per gallon.


--------

I have also also posted some pictures of the pumps and
plumbing found in the bilge below our TomCat sink.

******
 
How did you measure fuel flow? The best that any of us have gotten is about 2.3 miles per gallon on a plane. That is with fuel flow meters and with fill up to fill up, running at planing speeds the majority of runs--ie from fuel dock to fuel dock on 100 mile run. The only idle being leaving fuel dock and coming in to next fuel dock. I'll buy 2 miles a gallon...

Maybe I am missing something--but if you went 17.5 miles per hour, and used 5 gallons per each engine per hour--that is 10 gallons an hour or 1.75 miles per gallon--not 4 miles per gallon...
 
******

The input above was for just one engine.......
cut the above by a half for the two engines.....

two fuel tanks to fill.......at $3.96 gal....Yeks

******
 
***

Morning Charlie........

Yes..........your assumption is 100% correct.........

good to hear that the lady,
Lady KC
is close to normal :wink:

Thanks for your input.

***
 
matt_unique":7rx9z5wg said:
When you disengage the liquid tie bar with the valve under the stern/starboard access panel only the port engine will turn when you turn the steering wheel. What I do is align the starboard engine straight ahead, disengage the tie bar, then turn the steering wheel to align the port engine parallel with the starboard. Once done, close the liquid tie bar valve.
Click to expand...

The liquid tie bar valve is what I was needing to make adjustments with but did not even know how to describe our situation.

Awesome!!!
 
The correct method per the steering supplier, is to turn the engines all the way to port and raise them. This puts them both hard over. Then open the valve. If they are misaligned, you'll hear a clunk as they both drop onto their stops. Close the valve and resume operation. If you have to do this often, you have some seals leaking, probably in the rams.
 
Dreamer":2w2stojy said:
The correct method per the steering supplier, is to turn the engines all the way to port and raise them. This puts them both hard over. Then open the valve. If they are misaligned, you'll hear a clunk as they both drop onto their stops. Close the valve and resume operation. If you have to do this often, you have some seals leaking, probably in the rams.
Click to expand...

Wow, cool. Im going to the marina tonight just to try this!!!
 
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