Cat Fever Pictures Finally Posted

drjohn71a":3syap2kr said:
This all seems like a bit of overkill to me, as well as injecting an opportunity to foul both engine's filters with bad fuel accidently.

I mean, the thing holds 300 gallons of fuel... How much do you use trolling? At hull speed, that is about 6 gal per hour, or 50 hours of motoring. Or 300 miles of traveling without keeping track of fuel? I don't really see using one engine as a significant drain on either tank.

Each engine has it's own fuel monitor on the Honda digitals including flow, hours, total gallons used, etc.. So just look at your gauges and rest one or another of the engines if you want equal tanks.

And, if one tank has some water in it and you get in rough water with both taps open... now you have NO engines running while you go aft to drain the water from the filter bowl.

But, you guys have done so much great work to that boat that I really admire. I'm just more of an 'end user' boatwise. I want to spend minimum time working on the boat's hardware!

Thanks for posting,

John
Click to expand...

No boat of any kind, shape, or size with two engines and more than one tank should be without some method of isolating tanks or choosing which tank to use whether for balancing the boat or isolating a tank with a problem. No commercial vessel would ever operate on a one engine, one tank basis and neither should a recreational vessel since it severely limits your ability to deal with emergencies and failures.

If I'm in the middle of timbuk nowhere I want to be able to isolate a fuel tank that's ruptured, whose fittings failed, or that was contaminated and run both my engines off the "good" tank.

If the boat is loaded heavily to one side I'd like to be able to burn fuel off that side in order to level things out a bit.

If you do this when the boat is new you can run a tank completely dry before switching to the opposite tank; this keeps you from building up crud in the bottom of the tank which you can't do otherwise because in the one engine, one tank scenario you can not afford to run dry.

It isn't a complex system at all; it consists of three on/off valves designed for the job they do (that is, they're gasoline rated). There is an inline valve between each tank and the engine on the same side and one cross-over valve.

Three conditions exist (typically):

1) The cross over is closed and the two inline fuel valves are open...each engine draws fuel from the tank on its side.

2) The cross over is open and the port valve is closed...both engines draw from the starboard side tank.

3) The cross over is open and the starbard valve is closed....both engines draw from the port tank.

The thing is if you prefer to operate with each engine drawing from its own tank that's fine, just leave the inline valves open and close the cross over. You don't have to run through the cross over. The beauty of this system is that you can if the need arises; also if you prefer to balance tanks you can. Shoot...even the CD22 gives you this option.
 
Thanks Les for the extra info and sharing your expertise! I can't tell you how many times I've been impressed by, and life made easier by listening to your advice.

I was mainly thinking about the originally presented "problem" - uneven fuel use due to trolling. I had not backed off to see the total picture as have you.

As I mentioned, I am mainly just a "user" on these items. Maybe I can get some MidWestern mechanic to install something like this. I guess my main funtion so far in this thread was to act the fool to the point you had to clarify the situation!

Thanks again and success be with you up there in that beautiful area!

John
 
Les,

I agree with everything you said because it addresses all the safety related issues. But I also want the "fourth" scenerio, where one engine will draw from both tanks simultaneously. Since fluids take the path of least resistence, an ill-designed manifold could cause two engines to draw from one tank!

Therefore, my idea was to build:
1. An accummulator tank (brass pipe) about 2" inside diameter by 20" long
2. Provide a fuel inlet at each end for the tanks.
3. The two inlets will have ball-check valves, to provide a shut off from each tank and the built-in check valve will prevent siphoning from one tank to the other.
4. Located at the center of this pipe with be an isolation ball valve.
5. Two outlets to the engines will be mounted at each side of the isolation ball valve to keep them as close to center of pipe as possible.
6. The two outlets to the engines will have checkvalves to prevent siphoning any fuel from the non-running engine.

The purpose of the accummulator tank is to slow the flow of fuel travel so that it will feed either outlet to the engines and draw equally from each tank (reducing fuel taking the "path of least resistence"). The hoses from each tank will be cut to the exact same length and be routed to have the same number of bends to help assure an equal draw from each tank.

I will take this opportunity to add fuel/water separators to the inlets of the accummulator tank. Looks like there is ample room to mount this inside the transom area behind my bait tank location.

Why go to this much trouble? When I fish in the San Diego area, I travel to fishing grounds at night at 8-10 knots, leaving at 9-11pm, to get to fishing grounds by greylight (yes, 50-80 NM). We troll 7-9 knots from 5am-4pm, many times on one engine when trolling live bait.

After fishing is done, we run back to port as fast as we can. I am concerned that my tanks can get out of balance by losing track of how much time is trolled on one engine, or if one engine may be burning more fuel. After a hard day fishing, we don't want to limp back on one engine, nor put stress on my boat by planing on one engine.
 
Bad Boy":hc90g8bn said:
I am concerned that my tanks can get out of balance by losing track of how much time is trolled on one engine, or if one engine may be burning more fuel. After a hard day fishing, we don't want to limp back on one engine, nor put stress on my boat by planing on one engine.
Click to expand...

I must be not understanding something here in your scenario. Using the setup that Les devised, if the tanks are out of balance, run off the tank with more fuel until they are in balance. Since both engines are fed by the selected tank, I don't see how one engine could be starved of fuel unless you were running in the port engine/port tank, etc. configuration.

Warren
 
Warren,

I was trying not to guess how much to draw from one tank to balance out a list. The sponsons of a TomCat can camoflouge a more drastic fuel out of balance than what you can see. I also don't trust fuel gauges. My Mercury Smartcraft system doesn't make it easy to add aftermarket fuel flow meters.

If I get this done, I will report back my findings. Both fuel tanks will be filled to capacity. Then, I will run both engines, then one engine only and fill up at the end of the day to see if both tanks take the same capacity of fuel to fill. It will be interesting to see if it works.

By the way, does anyone know what is the real fuel capacity of a TomCat built in July of 2007? I read 130 gallons on the sales brochure and 140 gallons in my manual but some of the stuff in the manual looks outdated.
 
Bad Boy":2z4bjbo5 said:
By the way, does anyone know what is the real fuel capacity of a TomCat built in July of 2007? I read 130 gallons on the sales brochure and 140 gallons in my manual but some of the stuff in the manual looks outdated.
Click to expand...

I believe it is 150 gallons, 75 per side. Easy to determine now -- I will run one side dry and refill.

Warren
 
By opening the circular inspection ports by the little cockpit step near the aft cabin wall, you can see a white sticker with the gas tank specs on it. You may need a small mirror, but I could barely make mine out - 75 gallons - each side for a 2007 TomCat delivered December, 2006.

John
 
Excellent workmanship and planning!

My 2006 (completed May 2006) is 75 gallons a side--usable about 70 gallons. (both my measurement). We do rely on fuel flow guages, which we have found reliable, but have tubing aboard so we could switch tanks, or combine the tanks. We might add the crossover--and have used this type of system (but with a fuel transfer pump) in all of our long distance voyaging boats--both power and sail.

Some of the very first boats had smaller tanks, and there I believe that a few of the boats in late 2006 also had smaller tanks (65 gallons a side).

One question: have you had any water forced back up thru the single middle anchor locker tube? Susposedly this was the reason that this method of drainage was stopped by the factory. Perhaps the small tube under the clam shell has avoid this as acting as a baffle.
 
I'm with Dr. Bob in the concern over water entering that center drain tube. In good seas at speed there is tremendous pressure build up in that area. I would suspect water intrusion on a frequent basis.

John
 
I was reviewing the thread when I realized that I did not respond to the question about my single drain tube in the middle locker. But I have several months experience.

There has not been any water intrusion problems through this drain. However, there has been plenty of water come over the bow and enter the anchor locker through the deck hole that anchor chain goes through. The single drain has handled this without a problem. The key is the clamshell. The tube from the locker to the exit is at least 4-inches long to my recollection. You can spray a hose directly underneath and there is no water intrusion.

My two front lockers on both sides of the anchor locker do not have any mildew smell. I fiberglassed the wall openings and drain holes between the outboard lockers and the anchor locker. Now, they are truly useable lockers to store your clothing.
 
Thanks for the response. I am wondering how you got 4" between the inner anchor locker and external hole--looking at your photos it appears as if the hole you drilled on the stb side of the anchor locker goes directly into the outter hull at that point? Did you run the drain tube thru the area under the foreward bunk, and then out a second hole?

How many miles/trips did you take this summer? How did the boat do running out at 8 to 10 knots vs running at planing speed? (The reason I ask is that I find that 8 to 10 knots is a rather ineffecient speed for the Tom Cat--and wondered how your fuel economy was for that part of the trip--and the over all trip? Also how the the boat handle the seas, going out at late evening--when often there is some left over slop?

Thanks.
 
Bob,

I think the tube was longer than anticipated because of the angle of the front bow. Maybe it was only 2". I will measure and get back to you. There is absolutely no intrusion of water, it is too high off the water line. As I said there has been more water coming through the deck hole for the windlass.

So far, I have 100 hours on the engines. 150HP Mercury Verados. They have a lot of low end torque but they are much heavier than other makes. I purchased the Permatrims but haven't put them on. I run 17" Mercury Enertia props.

Unfortunately, I have not kept track of fuel efficiencies because of all the modifications and additions I am doing. My goal is to set this boat up as much as a "sportfisher" as I can. Everything I have done on my other sportfisher, I am trying duplicate, even added green underwater lights to attract fish.
 
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