I have a 13 foot fiberglass boat. Has two seats up front and open in the back. It is closed bow. The people I got it from made a HUGE gas tank and strapped it under the bow. Takes up alot of space and storage space is non-existence now. I have purchased two 6 gallon portables and was thinking of putting them in the back by the engine. It is a 40 horse. Question is, do I need the weight up in front to get it to plane or will it just take longer? I am not sure if the original design of the boat had a fuel tank up front or what...... I will post pictures later if I can.......
qxlooper
gas tank help
gas tank help
Last edited by Anonymous on Thu May 29, 2008 4:26 pm, edited 1 time in total.
RE:gas tank help
I'm not sure what type of boat you have, nor how heavy it is, but my guess is that a 40 horse motor will have no problem getting a 13 foot glass boat on plane, even with you, the motor and the gas tank in the back. I have a 12' aluminum, it weighs about 180 lbs, motor is a 15 horse, weighs another 90 lbs and the gas tank with a few gallons (6 gal tank, usually half full) is about 20 lbs. Plus me in the back (another 180) and you have near 300lbs (motor, me, gas) on the back of that boat. But that motor has so much zip to it I have never been close to having difficulties planing. It's gets that thing on plane in a matter of a few seconds, it's actually overpowered....Scary fast if I'm just in the boat, all that is in the water is the prop.....
I would put one gas tank right in the back, and if you could spare the room, stick the other gas tank in the front. But if you have no problems getting on plane with you and all the gear in the back and nothing in the front, then don't sacrifice that space up in the front and keep the tanks in the back. It' all depends on if your boat gets on plane or not. If you have trouble, move your tanks up to the bow....
I would put one gas tank right in the back, and if you could spare the room, stick the other gas tank in the front. But if you have no problems getting on plane with you and all the gear in the back and nothing in the front, then don't sacrifice that space up in the front and keep the tanks in the back. It' all depends on if your boat gets on plane or not. If you have trouble, move your tanks up to the bow....
Last edited by Anonymous on Thu May 29, 2008 5:36 pm, edited 1 time in total.
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Gisteppo
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RE:gas tank help
QX, the question will be whether or not she porpoises once the tank is moved.
Ideally tanks in planing vessels should be at or behind the point of the hull that is constantly touching the water (roughly the CG or just aft). Fuel tanks don't like to be pounded up in the bow, and can be subject to up to 4-5 G's of force. Having a tank in the bow works for some, but does require a constant eye on the tanks for signs of failure. You will often find manufacturers of boats putting the tanks amidships around the driver or within 3 feet of the transom.
As a test, pull el tanko grande out and put your new tanks right up against the transom. Don't fix them there, just set them in. Take her for a spin, and call it a sea trial. Drive in circles, fast stops, fast starts, different trim angles, etc etc. If she porpoises or shows bad manners, just slide the tanks further forward and restart the test.
I can 100% guarantee you that it will perform better without the tank in the bow, but where it goes precisely is more a function of hull shape than anything else. What boat is it? Photos?
Any questions, let me know.
E
Ideally tanks in planing vessels should be at or behind the point of the hull that is constantly touching the water (roughly the CG or just aft). Fuel tanks don't like to be pounded up in the bow, and can be subject to up to 4-5 G's of force. Having a tank in the bow works for some, but does require a constant eye on the tanks for signs of failure. You will often find manufacturers of boats putting the tanks amidships around the driver or within 3 feet of the transom.
As a test, pull el tanko grande out and put your new tanks right up against the transom. Don't fix them there, just set them in. Take her for a spin, and call it a sea trial. Drive in circles, fast stops, fast starts, different trim angles, etc etc. If she porpoises or shows bad manners, just slide the tanks further forward and restart the test.
I can 100% guarantee you that it will perform better without the tank in the bow, but where it goes precisely is more a function of hull shape than anything else. What boat is it? Photos?
Any questions, let me know.
E
RE:gas tank help
I was looking at it tonight and figured that I can put them behind the two seats up front. This would put them aft of center of the boat. I was out yesterday and running it full throttle and she was on the v, but any wake or anything shook the tank hard! i thought it was going to rip through the brackets that the people mounted the tank to. They put stryrofom up top to protect it from the bow, and three 2x4's inbetween the bracket and the tank. Not a very good setup! I was also thinking of finding a way to secure them up front for the weight, but the neighbor offered some bar weights if I had a problem. My other question is on the motor it has 4 holes for the angle of the motor in the water. right now it is pretty straight. Would moving it to the largest angle(closest to the boat) make it better to push the nose over? Or what effect do these different holes(angles) have on the performance? My daughter is 9 and wants to go tubing.... I figure I will have enough juice to pull her. She does 30 full throttle.
thanks for your time and responses!
I have electrical questions as well if anyone has any knowledge with 1968 johnson motors! Voltage regulator to be exact!
Gisteppo, I am thinking of coming to long lake next week to play with her, am only 20 minutes from there..... not sure if you will be around.
Qx
thanks for your time and responses!
I have electrical questions as well if anyone has any knowledge with 1968 johnson motors! Voltage regulator to be exact!
Gisteppo, I am thinking of coming to long lake next week to play with her, am only 20 minutes from there..... not sure if you will be around.
Qx
Last edited by Anonymous on Thu May 29, 2008 7:26 pm, edited 1 time in total.
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Gisteppo
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RE:gas tank help
Q, there are 9 Long Lakes in Wa state. You are going to have to put some miles on to come see me... (Spokane)
You should give it a whirl with the tanks aft, because they not only shake less, but you have the maximum bearing surface for the water to press against the weight of the hull right at the transom. I don't think you will need any weight in the bow, but if you do, just put your anchor, rope, spare tools, and all your goodies in the big bow compartment. That should do just fine.
As for trim, you have to consider what you are doing with the boat at the time. This is an extremely rudimentary synopsis, but for your situation it will be fine:
Starting at the transom:
1: Fast planing, low top speed, lots of spray.
2: Best overall holeshot, keeps bow down for chop.
3: Slower holeshot, but bow is up, most likely your highest top speed.
4: Probably too far up, will porpoise, if you can get it settled will go fast, but prop will eat too much air.
Trim is best explained on the water with someone having power trim on their boat.
Try pulling the kidlet with the motor as-is. If it won't plane with her back there, move it down to the lowest notch, but you won't want to leave it there. You might be surprised that it does fine. If you decide you need to be able to trim the boat, you can get aftermarket trim units that are small standoff brackets that give lift, trim, and some aft standoff to get better performance. CMC makes a nice one for smaller engines that has a bass boat jackplate look.
E
You should give it a whirl with the tanks aft, because they not only shake less, but you have the maximum bearing surface for the water to press against the weight of the hull right at the transom. I don't think you will need any weight in the bow, but if you do, just put your anchor, rope, spare tools, and all your goodies in the big bow compartment. That should do just fine.
As for trim, you have to consider what you are doing with the boat at the time. This is an extremely rudimentary synopsis, but for your situation it will be fine:
Starting at the transom:
1: Fast planing, low top speed, lots of spray.
2: Best overall holeshot, keeps bow down for chop.
3: Slower holeshot, but bow is up, most likely your highest top speed.
4: Probably too far up, will porpoise, if you can get it settled will go fast, but prop will eat too much air.
Trim is best explained on the water with someone having power trim on their boat.
Try pulling the kidlet with the motor as-is. If it won't plane with her back there, move it down to the lowest notch, but you won't want to leave it there. You might be surprised that it does fine. If you decide you need to be able to trim the boat, you can get aftermarket trim units that are small standoff brackets that give lift, trim, and some aft standoff to get better performance. CMC makes a nice one for smaller engines that has a bass boat jackplate look.
E
RE:gas tank help
All righty then, I understand what you are saying and will take the biggin out! It has to go! I will report back with my findings nd go from there! Thanks for your help! I will be out on Sunday or monday, as I have to go fly around for a couple of days!
QX
QX
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Gisteppo
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RE:gas tank help
Ill be curious to hear the difference in the boat.
Im home tomorrow if you end up in Spokane.
E
Im home tomorrow if you end up in Spokane.
E
RE:gas tank help
Ok, so I am late getting back to you all here! I took the gas tank out, and put in a 6 gallon red one. Put it up against the transom and moved the pin in the motor to 3 from the transom. took my daughter out and her friends to do some tubing. She planes beautifully and goes 30! I didn't expect that. Handles 100% bettr and no more thinking the gas tank is going to come loose and decapitate me All in all, one smart move and a BIG THANKS to all that replied! Now if I could just figure out the voltage regulator, I would be all set and put my boat together once and for all!
K
K