# How Much Weight Can the Boat Float?

Discussion in 'Education' started by yaasaay, Jul 6, 2011.

1. Joined: May 2011
Posts: 53
Likes: 0, Points: 0, Legacy Rep: 10
Location: saudi arabia

### yaasaayJunior Member

hi guys

can you tell me how can I calculate the capacity of float?

How Much Weight Can the Boat Float?

I know how to calculate the density of the boat but after that

for example

a canoe with dimension :
depth is 33 cm
and length is 366 cm
and width is 104 cm

and wight is 22 kg

then the volume is 33*366*104 = 1256112 cm^3

and to convert to m3 we division by 1000000

so V=1.256112 m^3

the density rule is (mass of steel hull + mass of enclosed air) / volume

remember the mass of enclosed air equal to 29

so
the density of the boat is ( 22 kg + 29 kg) / (1.256112 m^3) = 40.6kg/m^3

the density of water is 1000 kg/m^3

HERE I don't know how to calculate the capacity

the site calculate the capacity about 317 kg

look
http://www.acaldesigns.com/bhp/oldtown_canoes/stillwater_12/stillwater_12.html

I convert all the dimension from in and feet to meter and cm

and please correct me if there is mistakes

2. Joined: Aug 2002
Posts: 15,770
Likes: 1,197, Points: 123, Legacy Rep: 2031
Location: Milwaukee, WI

### gonzoSenior Member

You need to see what the rules, if any, ask for first. The rules will specify: reserve floatation, minimum freeboard, etc.

3. ### Submarine TomPrevious Member

So, 1.256 m cubed = 1256 kg.

Your canoe will float 1256 kg of total weight (mass) including the weight of the canoe, air, people, coffee cups, paddles, etc.

But at 1257 kg it will flood and sink. So, 500 kg is probably a safe limit minus all of the above. Therefore, maybe 250 kg?

-Tom

4. Joined: May 2004
Posts: 5,372
Likes: 255, Points: 93, Legacy Rep: 3380
Location: Italy (Garda Lake) and Croatia (Istria)

### daiquiriEngineering and Design

Only true if the that canoe is not a canoe but a rectangular block. The number you have obtained has to be multiplied by a so-called "block coefficient", which will depend on the shape of your hull.

Take a look at this site which eloquently explains the meaning of this coefficient (and many others too): http://www.oneoceankayaks.com/smhydro/hydro.htm

5. Joined: Nov 2003
Posts: 19,133
Likes: 490, Points: 93, Legacy Rep: 3967
Location: Eustis, FL

### PARYacht Designer/Builder

Look folks, wet nursing this fellow isn't going to help him. He's asked for just about every basic calculation and specification you can imagine thus far and I'm afraid someday he'll present his newly built masterpiece, 40 passengers and guests will board and the thing will drown 30 of them, because he refused to absorb the necessary disciplines.

6. ### FrostyPrevious Member

Eureka!!!

7. Joined: May 2011
Posts: 53
Likes: 0, Points: 0, Legacy Rep: 10
Location: saudi arabia

### yaasaayJunior Member

PAR really I don't know why you don't like me

Always when I asked something you want just to go out of the subject
And why do you think I don't have some basic things ?

I read but still there is somethings passive

and I can guess what you will response "" you asked for just about every basic.....''''

thanks

8. Joined: Aug 2002
Posts: 15,770
Likes: 1,197, Points: 123, Legacy Rep: 2031
Location: Milwaukee, WI

### gonzoSenior Member

Par thinks you don't have the basic knowledge because you are, for example, calculating the volume of a canoe as a rectangular prism. I agree with him.

9. Joined: May 2004
Posts: 5,372
Likes: 255, Points: 93, Legacy Rep: 3380
Location: Italy (Garda Lake) and Croatia (Istria)

10. ### FrostyPrevious Member

Well actually Im quite impressed, I could not learn something so complicated in another language based on a different alphabet. Not to save my life.

I cant help him but im still impressed. I think you should cut him a bit of slack.

11. Joined: May 2011
Posts: 53
Likes: 0, Points: 0, Legacy Rep: 10
Location: saudi arabia

### yaasaayJunior Member

12. Joined: May 2004
Posts: 5,372
Likes: 255, Points: 93, Legacy Rep: 3380
Location: Italy (Garda Lake) and Croatia (Istria)

### daiquiriEngineering and Design

I think Yaasay's questions have always been answered so far...

13. Joined: Jun 2011
Posts: 84
Likes: 9, Points: 0, Legacy Rep: 119
Location: Seattle, Washington, USA

### SaildudeJunior Member

Nice set of links for the Dummies Guide - Bookmarked - Thanks much!!

14. ### BostonPrevious Member

Your going to eventually come to the conclusion that designing a boat of any kind takes some pretty serious skill in order to get it right and not end up swimming. There are tons of good designs out there, you'd be money and time ahead by looking through them. I got the bug early on as well but eventually sorta came to my senses, sorta, eventually, maybe, not.

There is a guy in here Stan aka ancient kayaker who would probably be able to direct you to some yak plans that are easy for a beginner to figure out.

15. Joined: Nov 2003
Posts: 19,133
Likes: 490, Points: 93, Legacy Rep: 3967
Location: Eustis, FL

### PARYacht Designer/Builder

What we take for granted in most of the western world is certification, regulation and registration systems, imbedded in the industry to insure things are done properly. This isn't to say a novice couldn't manage to design a functioning jon boat, but it is to say that based on the type and number of questions you've posed so far Yaasaay, you have no where near the elementary skill levels necessary to design anything, including a boat.

I mean no disrespect in this observation, which I've previously stated, but would you travel to the top floor of a 50 story building in an elevator designed by someone who don't have 8th grade math skills? How about riding in an airplane at 25,000', designed by a guy that asked "how long should I make the wings on this project" prior to building?

Just like aircraft and elevators, boats place humans in an unnatural environment, one in which a problem or design flaw, can leave the people fighting for their lives, if not drowned. It's this basic premise that I assert my disdain for the free information offering you've gathered here. It's one thing to show you've the ability to understand the concepts and principles and the reasonable educational skills to absorb them, but you have not shown these skills. In fact, just the opposite and a complete lack of the necessary and rudimentary math skills necessary, not to mention engineering basics or hydrodynamics concerns. This scares the hell out of me and should also, anyone that dares ride with you, in your eventual boat.

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.