Weight distribution ?

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user 21876

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I am having second thoughts on my choices in battery and fuel tank.

I originally bought a U1 deep cycle, 24ish pounds and a 3gal fuel tank, 19ish pounds. I was really trying to keep the boat as light as possible but I (think I) need more weight up front. The battery and fuel tank are both up front under the deck. The boat porpoises with just me even though I have bent the full width trim tab down. After talking to several people, builders and dealers, the suggestion is to add more weight. A group 24 is about 45ish pounds and a 6gal tank will get me to 37ish pounds, but I don't know if that will be enough. I have room for a group 31 and up to 2 6gal tanks.

I am going to the lake with my big cooler and a bucket, my plan is to run the boat and keep adding water until I can run wide open with no porpoising. I really don't want to bend the trim tab any further if I can avoid it. Once I know much weight I need, then I can decide on a battery and fuel tank.

Is this a good plan or does anyone have a better suggestion. I am all ears at this point.

I am 170lbs, the motor is 120lbs and there is nothing else in the back of the boat. Currently the boat is running 22-23mph before the porpoising starts and I have the motor trimmed way down. The battery and fuel tank are 8' from the rear of the boat right in front of the sweep up to the bow.

Thanks Darryle
d7626cdba1eab2fea3bd46acf8e15e07.jpg


1244 Atchafalaya Outdoor Designs W/ 12hp Copperhead
 
I'd suggest playing with the trim angle on the motor. A few lbs in a boat shouldn't be that critical. You want the front end to be out of the water at speed (and to stay out).
 
I cannot get the motor to trim up because of the porpoising. I may have to bend down the trim tab more, but the weight isn't right in the front, it's too light.

1244 Atchafalaya Outdoor Designs W/ 12hp Copperhead
 
Jim said:
Or her...... :)


Sent from my iPhone using Tapatalk
Tried that, it stops the porpoising, but I usually hunt alone. Trying to find the balance point, where I can run the motor as designed and as shallow as possible

1244 Atchafalaya Outdoor Designs W/ 12hp Copperhead
 
Trim can be tricky... you need to find the sweet spot..... just adding weight is overpowering the problem but not correcting it... I'm not very familiar with long shaft motors like that, but it seems that just a slight change in the angle of the motor will have magnified results.... the sweet spot is probably very small... On either side of it you could have behavior like porpoising or plowing as you reach speed.
 
Well, I went to lake again today and forgot to take the cooler. I did bend the trim tabs down some more and that helped. I ran a max speed of 25.7 and an average of 24.3 in shallow water and 22.9 in deep water. The biggest issue was the wind, white capping and 21mph gusts, it was not fun on the main body of the lake.

I still have some more playing around to do and see if I can find a sweet spot for the motor to run.

Sent from my QTAQZ3 using Tapatalk
 
Does the hull have hook in it? Can you pound it out from the inside? Is it under a hull warrenty? No expert on mud motors but would a tiny trim tab welded somewhere on the back help hold the front down? I'd fix the problem. Moving weight is great. Adding weight is a bandaid. Nice little rig!
 
The boat is brand new and there is no hook. It has a full width trim tab and I have bent it down, but I think I may have went to far, maybe an 1/8" too far

1244 Atchafalaya Outdoor Designs W/ 12hp Copperhead
 
Hmm.. I guess you could have bent it down too far. That would force it down hard and then bounce up instead of it riding up to high and falling down. Foward this thread to the manufacturer. Most like to help a guy dial it in.
 
Have you tried adjusting the angle of the motor ? seems like that long shaft would still be pretty sensitive to the angle it's pushing. from the photo it looks to be up pretty high ? That's a long lever back there...
 
That is not the running trim position. It has a screw handle adjustment. When it is running planed out, there is roughly 1/3 of the prop out of the water, maybe less. I am going to the lake and run it again in the morning. I bent the trim tabs back to the original position and I am going to mess around with the weight distribution. I ran it for a couple of hours and it only used a little over a gallon of gas, so me and the motor builder agree that a 6gal tank is too big as the fuel would probably go bad before I could use it all.

It is sensitive to adjustment, I had know way to tell if or how much I was moving it on the fly, so now it is marked on the knob with a line. I am going to work with the base trim first and then add water to the cooler to find the weight sweet spot. 20lbs will equal me going from the U1 deep cycle to a group 24 and 30lbs would be close to a group 27.

I will report back in the morning after I run it.

1244 Atchafalaya Outdoor Designs W/ 12hp Copperhead
 

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