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no replacement of displacement? perfect size/ least draft

21K views 199 replies 34 participants last post by  JPHolla  
#1 · (Edited)
So I love to get skinny. and we can all agree there are way to many factors to take into account when building a boat from scratch. but this is my estimate for boat size vs. hull thickness. Now for guys who like to get into the least amount of water possible there is no replacement of displacement. basically extra wide and light weight, but if you want it to last very long it better be tough. if you run in rocks, logs, or a river setting where you might find yourself on a dumped piece of steel you better hope you've got a thick enough hull to stand up to the torcher.

For this theory/ draft estimate I will be comparing 3 hulls and 3 different hull thicknesses. all boats will have 32" deep sides and 72" floor with a 102"beam. keep in mind the density of fresh water requires 62.4sq/ft^3. so for every cubic ft of displacement it will float 62.4lbs.

displacements @ 8" deep.
1672-48.8 ft^3
1872-58.6 ft^3
2072-65.6 ft^3

given these displacement estimates multiply by 62.4lbs
1672-3045#
1872-3657#
2072-4094#

this means that every hull will displace that amount of weight @ 8" deep.

now lets explore hull weights. we all know most boats are .100 but a few make a .125 hull and evry once in a great while you will find a .190 witch one is best?
for these examples I estimated sqft of hull skin then multiplied by what each thickness of material weights. to keep it simple I divided total sqft and converted to how many 4x8' sheets each requires.

all weights are for 5052 aluminum sheet .100-45.7lb --- .125-57lb --- .190-84lb
16'= 5.36 sheets ---- ---- .100/ 245lbs ---- .125/ 306lbs ---- .190/ 451lbs
18'=6.01sheets ---- ---- .100/ 275 ---- .125/ 343 ---- .190/ 505
20'=6.67sheets ---- ---- .100/ 305 ---- .125/ 381 ---- .190/ 561

now that's just the skin, no frame work. So I come up with a flat rate to estimate interiors.
.100skin add 500lbs for frame work and interior of a 20' boat. for 18' on each thickness I will subtract 50# and for 16' subtract 100#

boat length- 16' 18' 20'
.100 245/645 275/725 305/805
.125 306/606 343/693 381/781
.190 451/651 505/755 561/861

^^^that is skin weight / full hull weight with interior.^^^

I come up with that rate of interior framing with the thought that the thinner the material the more frame work required. I may have went a little heavy, you decide.

so what is the best hull? would love to hear your opinion even if you don't like the last section about interior weight and think it might be off.



 
#156 ·
There's a guy over here that runs the river with an outboard jet. I want to pick his brain, but I can't ever catch him! I don't think it's a tunnel boat, but he's got it on a jack plate. Don't let all the haters, who have never fished our rivers, talk you out of the .190 bottom! I've got a hole in my .125 bottom to fix, and I wasn't even going fast.
 
#168 ·
Well there's his. Here's mine when it was still not all together back several years ago. mine is bigger, more power, goes faster, more expensive, drinks gas.. As far as doing what u want and being JUST RIGHT., his feels better mine. There's nothing wrong with mine, it does fine. Side by side his feels just right when u r fishing. Thought mine was JUST RIGHT. But now I see otherwise



Now here's another of his. Compare the 2
 
#176 · (Edited)
Justin (Afflicted) Thanks bro for the compliments. It is my boat and ive been on other airboats myself, not saying it because its mine, but I like the way mine does personally.
As far as gas goes, I used the same amount in my fan boat, YES my fan boat. That was a 1654 with a 13hp fan, a 2000w Honda genny and a 40hp yammer jammer outboard. It fished good also. But I can fish the same miles a lot quicker and not use more gas.
As far as the rake, Ive fished 4 people up front and it does good. The water doesn't push up the front like you would think. Only thing as of now that will change about my boat is my generator, my wife is supposedly picking me up a eu2000 soon.
 
#180 ·
Have you had a chance to figure any hull weights? I may have figured in a little too much bracing, but I've come up with around 1,850 lbs for an 1884, going off of your basic design description. I have no idea what a fan, and it's rigging weigh, but I've rough estimated the rigged boat, with 20 gallons of gas to be 3,100 or so, with no foam in the boat. That leaves about 1,000 lbs for people, gear, cooler, and fish. That, of course, is
without pods. You've really got me studying on this. Am I close, and if so, what needs to change for more payload? Or is that enough?
 
#185 ·
^^^^^^^^
X2 about the 36" sides with a normal transom height of 20" for a short shaft OB motor that's 16" above transom height and hopefully the top of transom is at least 6"-8" above waterline even loaded,and your safety factor isn't going to be increased much with the extra 6" of side height from a 30" to a 36" and would make it just that much harder to reach over the side for retrieving arrows stuck etc....
 
#187 ·
lol im not doing 36" sides. after seeing Bevers boat in person im not sure I could shoot fish from that far away from the water,lol
I just meant I wasn't sure what "payphone jones" boat plans were and tall sides could add weight to a boat.

I think 28" is the magic number for me, I run the ohio river a lot and 3-4' barge rollers are scary when they sneek up on you. how dare you doubt me brent, you know id class up the raised gunnel front and rear. lol just a little dryer ride, even if you let off the throttle to fast.



 
#189 ·
If I was to build another boat I would crimp the sides and possible taper it from 36" rear to 33-34" front. Otherwise I love it. In the south where mostly dink gar are shot I would run 28-29". Like carp commander said we fill the boat and have to haul them at a tournmanet in bad weather and its definantely nice assurance that you won't sink. 3500-4500 lb's of fish and 4 guys is not uncommon.