Vinyl Ester Resin

[OleRed]

I Love It  !   this is the first time I've used the vinyl ester resin, it's So Nice not having to hurry up and spread out a big lay-up, this stuff didn't even begin to tighten up for about an hour, mixing up 4 batches of 32oz each, by the time I got done and things cleaned up it was starting to smell good and getting tacky.

I layed the foam board in and taped it together to keep the resin off the hull, layed in the bottom part of the shell with 1708 stitched bi-axial, after the baffles are put in, epoxy applied inside, and the top is bonded, I will remove the thing from the hull, take off the foam board, and finish wrapping out the tank.

Before I install the tank for good, I've got just enough kevlar left to do a good lay-up between the stringers under the tank, just seems appropriate.

[WetRaider]

That's really cool, Red! 
Does that give you enough depth for a proper sending unit?

[OleRed]

I'll be installing a universal sending unit 3' from the front of the tank, they are adjustable for depth of the tank, but I do know, like the original tank, the only time the gauge will be somewhat accurate is when the boat is setting still.  The original tank is 6' long 8" depth and the sending unit id 10" from the front of the tank.

[Rosscoe]

Red,
what have you been using all this time if not vinyl ester?
Easier to work with sounds great!

[Jason]

That is really cool Red. Creative thinking. With a tank that long do you think maybe the pick up point should be towards the rear so you are not sucking air on take off? Or will it have some kind of baffle to prevent fuel starvation?

[dorelse]

So Red, what's the plan on 'capping' the tank then?  Put a bunch down on a flat surface, wet it all out, and adhere the top to the bottom and let it set up?

[OleRed]

Easier to work with sounds great!

I've always used polyester resin, actually, the vinyl ester is a polyester resin, just a much higher grade, several times the strength and a little more flexible, only thing about it is it takes 12 to 24 hours to cure out.

With a tank that long do you think maybe the pick up point should be towards the rear so you are not sucking air on take off? Or will it have some kind of baffle to prevent fuel starvation?

Yes, the pick-up will be in the rear of the tank, the fill and vent in the front, and there will be 5 baffles.

So Red, what's the plan on 'capping' the tank then?

I'll be bonding the top on the tank with the super steelflex epoxy after the baffles are in place, the top will bond to them also, then I will finish building, wrapping it up, from the out-side, two more layers.

[dorelse]

I don't know if this will help you in any way or not Red, but this is how my floor tank looks.  It has the gauge sender & fill/vent hoses all at the front, with 3 baffles in the tank.

It also has a 2nd rear vent next to the fuel pickup.  I'm assuming that's so it can vent whether the boat is in a bow up or bow down position.

[OleRed]

I don't think I've seen a tank with a veny in each end befor, but I can see it's advantage.

[dorelse]

Anyway, thought it might be an idea for you.  You can see the 2 vents just below the rub rail:

[Tmstibbe]

In a CSS 19, the in-floor gas tank has the filler tube, vent, and fuel pick up at the rear of the tank, and the fuel gauge sending unit near the front of the tank.   This is the factory set up, and doesn't work well at all for filling the tank while on the trailer at a gas station or on the water, and the set up for the gas gauge sending unit gives readings that are not at all accurate.

On the trailer and in the water, the floor of the boat is sloped to the rear, likewise the gasoline tank.  When pumping gas, once the tank gets a bit over half full, the rear of the tank is full.  The air vent is at the rear of the tank, and when only 1/2 full of fuel, the air vent tube becomes flooded and air can't escape, so this design causes gasoline to burp or even blast out of the filler tube while pumping gas.  There is no air vent at the front of this tank.

When the tank is as full as I can get it, the gauge might read 2/3 or 3/4 full.  I adjusted the sending unit several times, but you just can't adjust any further.  The sending unit is at the front of the tank, so when the tank is about half full, the sending unit float is sitting on the bottom of the tank, which shows up as empty on the gas gauge.

Imagine the tank lying flat level on the ground about half full of fuel.  If you tilt the tank slightly, one end is full of gas, the other end is empty.  The most logical place to put the gas gauge fuel sending unit would be at half the length of the tank, or dead center in the long axis.  You can tip the tank up at the front or the back, the fuel depth remains about the same at the middle of the tank.  I think a tank should have the fuel gauge sending unit in the middle of the tank's length.  And for venting, one at each end at the top of the tank.  And the fuel pick up at the bottom rear of the tank, assuming the boat will be nose up while running.  To be an engineer, remember, water flows downhill, every time.  Baffles can slow it down, but eventually gravity rules.

[OleRed]

I understand your suggestion about the sending unit should be in the center section of the tank, but that is not fesible in some of these boats, unless you put an access plate in the middle of the floor, and I'm not going to do that, but I will put an access panel behind the ski locker door for the sending unit, thats as far back in the tank I can position it, it will be in a better place than it was to begin with, right up in the front of the tank, and it too, like the one's you just described, is only somewhat accurate, depending on how the boat is positioned.  The rear vent on a long thin tank seems like a good idea to me, but if I were to use that plan on this tank, I think I would bring the hose all the way up front to the original tube, before the curl, I think that would prevent a surge from going over-board.

I understand the purpose of baffles being in a gas tank, and I'm not trying to "contain" any gas there, only to prevent a rapid weight transfer, remember, the tank I'm building is 10' long, and another reason I'm installing 5 baffles is to help re-enforce the tank structure to keep it from flexing when rough conditions exist, the baffles will have about 1/2 X 6" gap on the bottom above the keel and a about a 1" V at the top of each baffle. I'm really not concerned about the nose of the boat being lower than the stern while the boat is in the water, but it could be an issue with it being gassed up while it's on the trailer.

[thedeuceman]

I find that issue with the rear fill and only 1 vent interesting...
that's how the X-19 is set up, i may consider making some changes.

[WetRaider]

I'm only guessing here, because I have never worked with a sending unit - my 150 doesn't have one, and my previous SSV had one that worked reasonably well -
...
I'm wondering if the float level provides a variable impedance (resistance) causing the gauge needle to fluctuate in response to the change.  They aren't mechanical, like the speedos using the pitot tube.  If this is the case, and the gauge simply responds to impedance levels, I wonder if two senders can be wired to one gauge with the needle response being the "average" between the two impedances.  If wired in parallel (I don't know if it is possible, because I've never played with one), the mathematical or theoretical result in impedance should be the sum of both resistors divided by the number of resistors.  At least, that's the way I understand the application.  Maybe.  Anyone have a pair of sending units we can play with?  Are there adjustments on the gauge itself for sensitivity? 

[thedeuceman]

the sensors are essentially a variable resistor, connecting 2 in parallel will result in a lower resistance.
if they were both in the same position it would be half the reading of each, assuming the action is linear and low, or zero resistance is full (not sure which way they work) it would read 3/4 if there was a half tank of gas.
if one was way closer to zero the gauge would basically read what that one is.
if one was to build some kind of "summing amplifier" from a couple op amps it could work.
that's about all i kno about it 

[WetRaider]

Joe - I was kind of thinking along the same lines ... if two were in parallel, whatever the high impedance reading would be, the gauge would recognize half of that.  So if the gauge had a sensitivity adjustment, you could set it so that half the impedance would indicate a "full" read on the dial.
I had a speaker set-up where there were 3 dual coil drivers, each coil measured 6 ohms.  I put the coils of each driver in series (made 3-12ohm drivers), then put all three drivers in parallel (12 ohm divided by 3) for a single 4 ohm load.  I wonder if 4 sending units, two pairs, each in series, wired parallel to the gauge, would create a situation where the gauge responds as if the impedance were equal to that of just a single unit?  Getting a little out of hand ...

[Tmstibbe]

One more tank comment.

I previously owned a 237 Futura SL, 1989 glastron.  The 60 gallon gas tank was in the floor, lying along the centerline, as what we have been talking about here.  The boat had a fiberglass floor, no carpet.  The gas gauge fuel sending unit was located about mid-distance along the length of the tank.  The gas gauge worked well and was quite accurate, like what you would want.  The round plastic access cap was located in the floor, right between the back edge of the 2 front bucket seats.  If your were in bare feet, you could stub a toe every so often on that darn gas gauge fuel sending unit access cap.  I often thought there had to be a flush, flat access cap that would work better.   I never minded the location on the floor, but stubbing your toe in the walkway between the front bucket seats was no fun.  Someone might have something designed like the gas cap where you have a tool that fits into a very small narrow groove that creates a handle to turn the access cap.  Good luck and I hope the tanks being built will work well.   The gas gauge sending unit caught my attention, since I have had 2 glastrons that had accurate and trustworthy gas gauge readings, and then the CSS 19 with the poorest gas gauge set up and air vent design I have seen.  Every time I pump in gas, after half full, the air vent tube becomes flooded, no more air can escape. Then I get a blast of gas coming back at me from the fill tube.  I hand squeeze the gas into the tank at a very slow rate, place paper or cloth towels to catch the burping, but yet, have a mess every time down the side of the boat and trailer.  Other CSS 19 owners have told me they have the same thing happen to them.

[OleRed]

75 degrees yesterday here in Oklahoma City, 29 degrees this morning, 30mph w/gust to 40  rain turned to sleet, our power went off 9:00am,  1/2 of ice  stuck to the trees, a couple limbs big as my arm broke off  a tree in my front yard, one landed across the hood of my neighbors truck, I hooked the phone,tv and
computer to my 800 watt inverter, brought in the propane heater out of the house boat, power came back on about 4:30,   high temp today was 39 degree's.  I did get a couple hours work in on Gary's boat, and when I came in I seen on the news there were two or three Tornado's in St Louis area,  Wow !  my day wasn't bad at all,  sure hope all is well with Gary, he live's in St Louis