Nautical Design

[TheGreenGoblin]

Clearly Squiffy Pussy 2 will need neither impeller nor propellers. The good ship will be entirely hippo powered. At the click of Ex-Ascot's fingers, two ribbon bedecked hippos will take up the golden harness and will pull the good ship and all those who sail in, and on, her, G's & T's and all, across the vlei, to the immortal sound of Caruso, who is known across the Southern Hemisphere as the hippo God. The local's will drum and prepare feasts in honour of the ship and her good denizens come passengers... while an African moon smiles beneficently down upon their good health and happiness.

[Undried Plum]

If you fitted a bulb nose on each side it would tend to push water down the middle. Catamarans don't use bulbous bows but knife form.

The present configuration is doing that anyway.

What bulbous bows would do would be to reduce the bow waves. They are actually quite common on higher performance powered cats.

What I don't know is how to make a shape that would be easy to make with basic materials and techniques. Compound curves are out of the question for bush engineering and I've never seen a bulbous bow that doesn't have compound curves.

The greatest part of the induced drag on the present design is from the aft end, not the for'ard. That's where canoe fairings would make a significant improvement in drag reduction and a noticeable perf improvement at full throttle.

It'd be interesting to see a before and after comparison, using GPS as a log (speedometer), to show the improvement produced by the four aft fairings. I reckon (guess) about a 5-10% improvement at full throttle. Later adding for'ard fairings would be interesting, but I suspect that the further improvement would be little more than one or two percent.

What water speed does SP3 make at max chat in the present configuration?

BTW, I'm pleased to see that nobody's made the mistake of suggesting a bigger donkey. All that would do would be to make bigger waves and guzzle more fuel.

[ian16th]

I wish I'd taken more notice of the vessel design when I did the Vic Falls sundowner booze cruise.

Gotta admit, the vessel design wasn't high on my priority list.


The one we were on was something like this:

But this one has rustic appeal:

[Pontius Navigator]

For the bow, avoiding complex curves, how about two oil drums cut in two length ways, then joined end to end making a rounded section that could be welded to the present flat plated bows?

[G-CPTN]

cut in two length ways, then joined end to end making a rounded section

?

[PHXPhlyer]

One thing that Ex-A mentioned but hasn't been addressed are the aft outboard drums.
Instead of a deflector plate I would suggest cutting drums diagonally so that full circle end butts up to the front drum and tapers into the next drum forward-inboard.
A plasma cutter or oxy-acetylene torch would be helpful to fit the taper.
My 2 cents free of charge in exchange for a future cruise aboard the good ship (soon to be better) SP III.

PP

[Pontius Navigator]

cut in two length ways, then joined end to end making a rounded section

?

You will note that at one end, I thought the box, but PHX seems to think stern, there are 4 drums across the beam. My suggestion was to round the flat barrel ends by fronting them witn a pair of half barrels.

[Undried Plum]

Then you'd need to form a fairing ahead of those half barrels to avoid producing hellish eddy currents which would drag like parachutes.

[G-CPTN]

What's the planing speed?

[llondel]

For working over water, you need to have a tray in the water under where you're using the tools, then hopefully anything you drop will land on the tray and can be retrieved. That's probably where to have the magnets, rather than in the gloves.

Can't you hire the local crocs to do the work? "Fix that to the bow and make it snappy."

[G-CPTN]

There are videos online of people 'magnet fishing' using powerful (neodymium?) magnets capable of retrieving heavy metal items from deep water.

[izod tester]

The clip shown here shows a canoe made from a plastic oil drum, but the principle should work with metal oildrums if you can weld the joint at the prow.

[bob2s]

https://pontoonopedia.com/what-are-pont ... g-strakes/
The above may be of some use,would be easy to fabricate and install if you can get the SP2 far enough out of the water.

[Ex-Ascot]

Thanks again every one. Addressing the bow and the consensus of opinion that a 'knife like bow is needed. I would suggest that 'Barrel 2' below would work and a relatively easy thing to construct and fix.

I am still in a quandary about the stern. PHX I like your idea presumably as Barrel 3 diagram below. Obviously the base has to be angled. As you can see I have been playing with plastic bottles. These are similar to the drums right down to the ridges. I can't see how we can fit the extension flush with the ridges and also it would involve welding underwater obviously this can't be done.

The plan is to fix using a band that can be tightened up on the existing barrel. Also easy to remove if necessary.

A canoe like extension to the aft drums will surely create drag on the inner side of the canoe? Still snookered here.

UP we normally cruise at 75% which gives around 2.5 kts. Walking speed. Our handheld GPS has been stolen twice. The first time they couldn't get it to make a phone call so left it somewhere and we got it back. The second time we didn't.

Edit, just seen your post Izod. Problem with this mentioned above with drag on the inside of the 'canoe' also above we can't weld underwater. As said i am snookered here.

[TheGreenGoblin]

I suggest that we turn to this chap for some advice...

[Boac]

Don't you think it might frighten the Hippos?

[TheGreenGoblin]

Don't you think it might frighten the Hippos?

True, yet they are also depressed as the notion of them powering SP2 has been completely ignored! Caruso would be depressed as well if here were alive...

[Ex-Ascot]

OK, just had a meeting with the welder friend. Put all your points to him guys (thank you again). He is going with the knife edge bow it will be a sealed unit. He wanted to cut it back top and bottom so that the length of the blade will be the same as the diameter of the barrel. I have said that we prefer it to be longer. Think that it looks pretty aggressive and we mean business (Hippos). Unless anyone can see a problem with this.

Think that we have a plan for the stern. Cut the barrel diagonally as above. Then weld a plate over the open part flush with the case to make another sealed unit and fix it with the longer side flat with the boat as per diagram.

G.G The former owners had a quadraphonic sound system on board, speakers still there, but don't think that they were featuring Caruso. No idea what they were blasting across the lagoon for their S.A. kids but they were not very popular, even with the hippos. 19 seen up lagoon on Thursday, this is 3 kms away.