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Episode 058 – Thinking through design problems of the Hammock Boat.

In Episode 53 we talked about a Hammock boat.   In some other episodes we talked about the buoyancy of PVC pipe to create the pontoons.  In this episode we discuss the other problems we may have with this boat and things to be aware of.

First, the announcements:  I checked the e-mail subscription thing – it works alright. I misunderstood something in the audio. However, when you do subscribe it sends you to the About Page… Why does it do that? I don’t know… Maybe I can modify that. I will try.

2nd Announcement: Please send me an e-mail to garyfox@create-and-make.com describing what kind of information you would like to get out of this site. I have several directions I can go right now. Also, I would like to know if anyone out there would like some simple videos describing how to manipulate equations (Algebra). We probably will be getting more equations soon and I don’t want to leave anyone behind.

 The Hammock Boat.

The main concern: Would a cross wind possibly capsize the boat? In other words will the center of gravity be high enough that it can shift outside the down-wind pontoon area and tip the boat like a domino being pushed over?  We will have to make a lot of assumptions.

First Assumption: We only have to worry about the front view of the boat. On the side view the pontoons go the full length and will spread the load in that view. The concern is the center of gravity in the front view. Will it be high enough that a small cross wind can cause the up-wind pontoon to lift and capsize the boat?

Assumption 2: Components affecting height of the center of gravity:

  • The hammock frame: It will be whatever it will be. There is not much we can do about that one. We will just have to estimate at where the center of gravity will will be and the weight of the frame.

Assumption 3: The cross members from the frame to the pontoons: In this case heavier is better, because this weight will be low. However, we don’t want to get insane because we do have to support this weight with the pontoons. Probably, pine would be fine for this purpose. We will figure a 2X4.

Assumption 4:  The boat will be assembled at the dock so the cross members can be as wide as we want and still carry. The only real limiting factor is getting into and out of this boat.

Assumption 5:  The frame will have to be extended upward so we can attach the sunscreen. Lighter is better here because this part of the boat will raise the center of gravity.

Assumption 6:  The hammock and person sitting in the hammock will have to be thought of separately because these can swing in relation to the hammock frame. This will create an arc within the arc of the frame being tipped. (See Picture).

Assumption 7: Cross force vs. Wind Speed: This is going to be almost impossible to determine, so for the initial calculations we will just calculate cross force. Then we can try to find some way to estimate the cross wind to create that force.

Assumption 8: When calculating the effect of the person and hammock we will have to assume both a heavy person and a light person. The heavy person will keep the pontoon from lifting as easy as it would with a light person. However, a heavy person would cause a greater shift in center of gravity once the pontoon lifts. We will assume the light person at 100 lbs and the heavy person at 200 lbs.

Assumption 9: We want the sunscreen to be as tight as possible to keep it from catching the wind like a parachute.

The next post on this will be estimating numbers to every thing we have talked about in this one.  In the future we will have to talk about the money we are going to have to spend to build this thing and after that, what ways can we save money on this.

It is a nice little puzzle… I hope you have found this post enjoyable.

Gary

 

A note about this: After creating the audio and thinking about these possible problems I looked at the picture very closely. The designer of the original boat has solved many of these problems already.

 

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2 comments to Episode 058 – Thinking through design problems of the Hammock Boat.

  • Gary

    I am getting lots and lots of it also….I have just come up with a new rule and will announce it today. Unless I see something in the comment that shows me that some one has read that article. It will get marked spam. I hate that I have to do that, but I am sick of people abusing my site. It their comments do not get displayed they will have no reason to comment and it will eventually stop.

  • Gary

    Send me an e-mail to my contact information…. garyfox@create-and-make.com. I will try to point you in the direction I have taken.

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