I've made designs for a small creek boat I want to make!?

Question

I want to make a small boat I can float in a small creek. I've made designs for it, I was just wondering what material I should make it from? From plastic sheeting? Remember this isn't going to be going over rapids. the creek rarely is deeper than two feet and the fastest it goes is a fast walk. I also would like it to be light but that I don't really care about.

Answer 1

3 mm or 4 mm marine ply will be ample , Make a smaller one out of balsa wood  first to see if it will float .

Answer 2

Show your dad this site; http://www3.sympatico.ca/herbert.mcleod/...

Answer 3

That is a great project... and a great idea...

     I suggest that if you can, you use thin plywood, and boat building epozy.  This is probably the easiest method that will result in the strongest, lightest boat.  It will out last your kids when you grow up and have some and even their kids. lol

     So, I am going to refer you to two sites... One is Glen-L boat plans, designs, and builders... I know, you already have your plans, and that is great - build them (if they are going to float of course).  But this is an excellant site to learn and see what methods, and materials are readily avaliable to you to build your own boat.  It is a great informative site - especially if you have never built a boat before.

The second site is my own... I live aboard on my vessel "SummerWind" which I built.  There are pages there that show the progression (with pics and descriptions) of building my boat's hulls...

Here are the links:

http://www.glenl.com/

http://boatwrights.org/

Now... as for as "floating" is concern -

They key to "floating" a boat is "bouyancy".  Anything (as we know, even steel - will float if you give it enough bouyancy).

So, remember this old boat-builders saying:

"8 pints, 8 pounds, the world around..."

For bouyancy calculations, 1 pint = 1 pound, therefore

8 pints = 8 pounds.  There are 8 pounds in a gallon and 8 gallons in one cubic foot...  Got that?  You should have had it all in 5th grade math and science...  (Notice, we deal in all "eights" here - so it should be easy to remember)...

Therefore, 8 pounds in a gallon, 8 gallons in one cubic foot, and 1 cubit foot of sea-water therefore weighs 64 pounds.

And this is the KEY... to floating your boat.  It takes 1 cubic foot of space (or air) to float 64 pounds of weight on sea (salt) water...  But in your case, we are going to use 62 pounds because fresh water weights just a little less.

So, will your boat float?  The answer to this is to add your weight, plus the weight of all the materials you use to build your boat, plus the weight of any equipment, supplies, and additional passengers (if any) that are going to be on your boat...  and get a "total weight"... divide this number by 62 (weight of 1 cubic foot of fresh water).

Now your answer will tell you exactly what amount of space you must have below the water, to float the rest of the weight above the water....

So, if you weigh 112 lbs, and you are using plywood to build your boat...  In 4' x 8' sizes - plywood weighs 25 lbs per 1/4 inch thickness.  So, if you are using 1 whole sheet and half of another, of 1/4 inch plywood - that would weigh 38 lbs. (I always round up.)  Now lets say you use 12 lbs of glue (thats about a gallon of epoxy with a half gallon of hardner) and another 3 pounds of screws...  and you have an additional 35 lbs of gear and equipment.. ie, paddles, binnoculars, spear gun, fishing gear, radio, laptop computer, ice chest full of ice with cool aide, sandwiches, coke, cookies, etc...  

So, if we add that all up, you have 200 lbs you need to float above the water... so you need 200 (total weight) divided by 62 (weight per cubic foot of fresh water you must displace) = 3.225 (so lets round up) you will need 3 and 1/2 cubic feet of space to float you, and all your "stuff" on the water...

Now, one more thing you mentioned... and that is the "creek is rarely more than 2 feet deep... "  So, now you have to get past the shallow water or "boat draft" problem...

We know now how much floation we need ie: 3.5 cu. feet, but now we need to "shape" that 3.5 cubic feet so our boat will not sink so far in the water it hits bottom before it has a chance to actually "float"...  So, here you have to decide how deep your boat's hull (or bottom) can be in the water... and in your case, you want it to be no deeper than the very shallow most part of the creek... So lets say that it 6 inches...

So, you need to take your 3.5 cubic feet and flatten it down, so that it all fits no more than 6 inches below the water...

To do that, you need to take your 3.5 "cubic foot "foot's print" and double it... - as your 1 cu. foot "foot print" is 1 foot wide, 1 foot long, 1 foot tall... now we want to make it only 6 inches tall... so, lets cut your cubic feet in half, and lay those halves next to our existing ones - so they will be flat on the water...  Now, here is where the "fun" starts...  Now you know that for your boat to float no more than six inches in the water, you need 7 square feet of "flat" bottom area on the water...  If you want you boat to float only 3 inches of water, you will need to double your flat surface again and you will need 14 square feet of bottom area...

Hint... If you want to use your boat more that a few months or so...  don't build your boat to your weight today... add a few lbs so you won't hit bottom next season... LOL  



Happy and Safe Boating!