Cautionary Words - Watch the weight of your mods...

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wasilvers

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So I built my boat out years ago. I used some heavy materials - 3/4" plywood for all the decking. a 2x12 for a stringer(?), etc. I fish with some 300lb+ guys and wanted everyone to feel comfortable. In the final setup I had 2 batteries (biggest I could find). One in the rear to start the engine and run some electronics. One just in front of the console - to run the trolling motor.

Late last fishing season, I took out the front battery and put in wiring to the rear - just using one battery in the boat. The removal of weight in the front, and loss of 60-80 lbs increased my boat speed by FIVE mph. It's not a speed demon, but I was just under 25 mph and last trip I was just under 30 (16 footer, 50 hp, under propped). Wind was not really a factor in this test.

Now I'm considering redoing the entire boat with weight control in mind. Might be easier to start another boat, then I can fish in between working. :)
 
Removing 75lbs out of the first 4ft of a 16ft boat is the equivalent of removing around 300lbs from the last 4ft. Look up about a boats center of gravity been a while but seems like I ready something in one article and I figured it up that for a 16ft boat the center of gravity needs to be around the last 3 1/2ft of the boat for best speeds. Like I said been a while since I ready up on this but I have removed 75lbs from the front of my boat and picked up 2-3mph. I can have 150lb person set on the bench beside me and I might lose 1mph so the math works out about right for 75bls in the front vs 300lbs in the back and the gains and loses I've seen adding weight and removing it.
 
This is absolutely true!

Think about the higher performing bass boats. They all put the batteries and tank in the stern area, rarely (if ever) the bow.
My boat, with a 70 lb trolling battery, runs right at 29mph (25 hp). Put a 40 lb Optima in it, still runs 29mph. Put a 10 lb lawn mower battery in it, remove the tackle, seats, trolling motor, gear (about a 200 lb weight loss) and it still runs right about 30 but it might do a little more with a prop change. BUT, at one point I thought it would be a good idea to move the battery to the front along with the fuel. LOST 4 (FOUR!) MPH and it made it feel like it was down 10hp. I had a 15hp on it at one point and that is exactly what it felt like. Put it all back where it was originally (behind the seat) and it came back just like it was.

That said, if your hull "likes" to porpoise a little and you can't trim it, you can move weight forward to "help" the issue...but IMO, it's a crutch for a poor setup.
 
I just redid my front seats and found the PO used a huge piece 3/4" plywood to hold the foam up under both seats. He used that old rock siding material to fill a big gap in front of the front seat. Between that an old soggy foam It lost a bit of weight. Everthing that goes in the boat gets weighed. Everthing that goes in the camper or on the sandrail does as well. It's hard to see and feel weight but if it's on a scale you know. Yard sale postage scale or old bathroom scale is good enough for the shop. I just picked up a composite prop for cheap and its lighter than my aluminum spare. It may not be much lighter but guess which one is in the boat? 60hp on 16' saw almost 38 mph with a 17 pitch prop. I run the 15" for more punch and drivability but it's still in the low 30's.
 
3/4 ply is way overkill, 1/2 is plenty usually unless there is inadequate bracing, aluminum decking is lighter still. I would use aluminum bracing at least for framing, the wood really isn't that heavy if you stick with 1/2". I only have one group 27 battery that I use for my hand controlled trolling motor, it lasts 2 days. it won't throw you out of the boat but usually is plenty for fishing.
 
Since 1985 the biggest heavy sacrificial zinc on my outboard looked brand new. The outboard has other zincs and I'm a fresh water boater. I was surprised it was over two pounds. That's two pounds behind the boat transom. That's 2 lbs off of the trim motor, off of the trailer, wheel bearings and tires. Over the next decade I think the benifit of shedding the weight will be worth it especially every time I push it off of the beach.

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It all depends on what you want to do with regard to weight distribution.

The more weight you have forward the slower you'll run, but the less water your boat will draft in the back.

But any weight reduction in a tinny is a good thing. I'm going to a small gas tank and a motorcycle battery. Should save about 50 pounds.
 
Blake said:
It all depends on what you want to do with regard to weight distribution.

The more weight you have forward the slower you'll run, but the less water your boat will draft in the back.

But any weight reduction in a tinny is a good thing. I'm going to a small gas tank and a motorcycle battery. Should save about 50 pounds.
I looked at motorcycle batteries today but they wanted $80 bucks then I saw the lawn tractor batteries. $19.97 at Walmart. 230 CCA. I've got to bring them an old battery from the junk pile to get a $12 core charge back. It weighs 16 lbs. It starts the engine and runs the trim just as well. I keep a little 5 or 10 watt solar charger on it so it should stay charged enough to keep working. The old battery was almost 50lbs. For 20 bucks I took 35 lbs out of the boat. What else will shed a few pounds?

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Good thread.
I just rebuilt a 16' aluminum boat. I used 5/8" plywood, replacing the original 1/2 plywood. I moved the 30 gallon live-well from the port side to the bow. I put a Group 29 battery for the trolling motor in front of the live-well. In this configuration the boat sat a little bow down, even under power, with or without water in the live-well. I moved the group 29 trolling motor battery to the rea battery compartment, just in front of the tiller motor. That altered everything. Bow sits higher in the water, boat travels bow up slightly above level while on plane, just where it should be.
 

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