Upright floating boat hook

[zauberberg]

Not directly a boat design, but connected to boats and stability!

Anyone interested in building his or her own upright floating boathook? There was ago an article in WBon the topic a couple of years ago, giving some empirical data for the problem. I thougt it would be interesting to solve the problem theoreticaly. It works:




Here is how you use the diagrams shown below: Get a nice boat hook fitting and weigh it to get its mass. Select a wooden handle in terms of diameter and wood type and, using the upper diagrams showed below, find out (for your hook mass, wood type and handle diameter) the maximum length of the handle allowed for a stable, upright swimming boat hook (if the fitting is attached!). The corresponding floating height (i.e. the length of handle out of the water) can be seen from the next, lower diagram in the row. Shortening the handle is possible, and will not affect its ability to swim upright - but will give lower heights until it finally will sink.



You may want take out your spokeshave to shape the part of the wooden handle which is out of the water according to the sketch below. If you do so, you will increase beauty, usability and swimming height. How much swimming height will you gain by doing so? See the lowest diagram in the row.

Did I explain well enough?

[donald branscom]

Why not just tie a lanyard on it.

[J. Dillon]

Or you could just buy one here:

http://www.woodenboatfittings.com.au/jack.htm

JD

[Ian McColgin]

I make mine the very simple way.

Eight side and then round a pole of the length you like - 8' for the average bronze hook end works well - to a diameter an nudge bigger than the outside diameter of the large end of the hook.

Shape a cone at one end to exactly fit the hook socket. Temporarily attach.

Go to the water. Holding the pole empty end gently lower the pole into the water vertically till you're just balancing it upright but the pole is basicly floating. Mark the waterline before it drys.

Back at your shop start planing the pole making a nice waist as narrow as you dare near the hook and tapering out to full size at the waterline, then tapering again to the end of the handle. The goal here is to remove bouyancy deep below the waterline and remove weight that will be in the air above. Of course this is an approxomation but it will work.

Added good touch - put a groove along the pole that's alligned with the hook. That way in the dark you can feel the orientation to pick up the mooring pendent or snag the handle on the dog's life jacket.

G'luck

[KAIROS]

Good thread. Here's a different perspective on the original poster's scheme....

About 24 years ago (after reading that article in WB) my Dad bought the bronze fitting from the WB store, and it came with the drawing for an ash pole. It's now on my project list.

[are their copyright issues on a forum like this?]

[zauberberg]

Kairos,

yes, this is the how-to that comes with the WB hook. It gives the solution for the given hook of about 250 gr and an ash pole of 11/4'' diameter.

However, hooks availiable on the market vary significantly in weight. To make sure in advanve, that hook seen at the chandler in combination with the pole found in the garage's corner will result in a stable, upright swimming boathook with useful swimming height over the water is the purpose of the diagrams above.

Example: Using not ash but fir for the pole in your example (same diameter) would result in an significantly shorter possible lenght of the hook: 1,25 m instead of 1,80m.

[KAIROS]

You just bumped this up on my project list. I despise the one I have now.

[CapnJ2ds]

Good heavens! Formulas, graphs and plans for making boat-hook handles? Isn't this a variation on the ancient art of splitting hairs?

"When I were a lad"* wooden boat-hook handles were all there was. Mostly they were just strait rounded poles, tapered at one end to fit the hook casting. Some were simply square-section timber, only rounded in the taper. Most were bare wood, plus maybe the occasional dose of linseed oil; some were painted, a few were varnished on the flasher boats.

They all floated, without benefit of calculation, graph or plan. I should know - I've dropped a few overboard.

You used to be able to buy shovel handles that did nicely for mid-length boat-hooks; dunno if you still can.

*"When I were a lad": My nearly beloved offspring assure me that this period was between the domestication of fire and the invention of the wheel.

[Breakaway]

They all floated, without benefit of calculation, graph or plan. I should know - I've dropped a few overboard.

Insane right? Well were all a little nuts, choosing boats as a passion. These hooks float upright, making them easier to grab when dropped OB.

FWIW, you can use a cheap aluminum boat hook and jam a fishing sinker in its handle end to achieve the same effect. But where's the fun in that?

[Ian McColgin]

CapnJ2ds and I agree that the formulae don't really help with varying densities though we disagree as to the bad old days - I never saw a wooden handled boathook that floated verticly until I made one inspired by happy accident while I was refinishing an old hook.

Whatever pole length assuming that the hook is in the weight general range for that pole length, the only fear you have with my approach is the very unlikely chance of making the waist too narrow. In general a boat hook is not a peevey and should be used almost entirely for pulling and a little straight line pushing.

[Thorne]

In general a boat hook is not a peevey and should be used almost entirely for pulling and a little straight line pushing.

Wot? Mine gets used for all sorts of stuff -- like using the handle-end for pushing the CB down when it gets jammed from mud or gravel, funky whisker-pole, and fishing out hats lost overboard.

But I do need to test how it floats, and possibly grind off some of the metal from the hook end if it won't balance correctly.

[wizbang 13]

Billy Ray Simms (former wbm editor) was in Bermuda about 15 years ago showing me his boathook. It was a prototype from the magazine article. My buddysays,pretty cool,can I try it, he threw it into the drink like a spear,straight down. It never came up,we figured it stuck in the mud 25' down. Probably still there. He was ,and is, a good sport.

[Carl Cramer]

Billy Ray Simms (former wbm editor) was in Bermuda about 15 years ago showing me his boathook. It was a prototype from the magazine article. My buddysays,pretty cool,can I try it, he threw it into the drink like a spear,straight down. It never came up,we figured it stuck in the mud 25' down. Probably still there. He was ,and is, a good sport.

So THAT's what happened with my boathook! Bill Ray never told me.

I miss him, but he's doing very well.

[Ian McColgin]

Re wizbang 13's tale - same happened to me when I showed off one day in the cove. Lucky for me low tide revealed it, top still underwater but visible. Ever after I would drop it in horizontally and let it tip itself up.

[Michael D. Storey]

When I read that article, I didn't have a boat, but I built one, because it was an easy build, I had a small child that I needed to amaze, it looked nice, it worked every time...
Isn't that enough?

[wizbang 13]

It was actually Stevie Hollis ,Sailmaker ,"Ocean Sails",who chucked it.

[zauberberg]

Ian,

you wrote:

"... Back at your shop start planing the pole making a nice waist as narrow as you dare near the hook and tapering out to full size at the waterline, then tapering again to the end of the handle. The goal here is to remove bouyancy deep below the waterline and remove weight that will be in the air above."

I wondered whether removing volume below the surface near the hook as you desribe it has the desired influence. Obviousely bouyancy is reduced, comparatively more than weight (wood is lighter than water!), having the direct consequence, that the hook is sinking deeper into the water. This is not what we want.

But in looking closer at this problem via calculation it turns out, that by reducing volume near the hook as you descibed, both, center of gravity (cog) and center of bouyancy(cob) of the hook in its new, deeper floating position are moved upwards, but cob more that cog. This increases stability, and gives oppurtunity now to increase the lenght of the pole until the stability limit is reached again. The result is a a longer pole that floats higher than before. So you were right, Ian, and I learned something.

You also wrote:

"CapnJ2ds and I agree that the formulae don't really help with varying densities though we disagree as to the bad old days"

What formulae are you taking about? I gave diagrams, no formulae. And what do you mean with the problem of "varying densities"? The influence of different specific weights of the pole material? Take a look at the diagrams again: I gave two rows of solutions for a light and a heavy wood. For any intermediate values a first solution may be found by interpolation.

[Ian McColgin]

In the event, the hook ends up floating upright very close to the same waterline as it was floating upright but supported to the verticle before finishing.

The reason I like my empiracle for that stick and hook approach is that different woods I've used have different densities and even within the species there are variations. And the hooks - it's a bit surprising how they vary.

It's be a couple years since I made my last one and my workshop is on the boat so I should add that my planing is accompanied by quite a lot of test floating.

Not really thin as far as you dare in one fell step. Shave a bit of waist. Test float. Maybe shave a bit above the waterline. Test float. Ease to the shape.

So I'm glad your question forced me to recall more accurately the process.

And you're right, using a diagram, even interpolating, is not the same as a formula. Apologies.

However it's done, I deeply feel that two important features go into a proper boathook:

Floats vertically; and

Groove along the handle so you can orient the hook in the dark.

If a hook does not have both features, it is to me of no greater value than an aluminum pole, even if it has fancy varnish and lettering.

[donald branscom]

A stability curve graph on a boat hook!!! Now I have seen it all. Whooooooo