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[Guest625101138]

Originally Posted by I57

Congratulations Rick on finishing the Murray Marathon, I see from the results you came 2nd in the UNR1/OV50. What sort of boat did the other guy have?
The heat would be a challenge on its own let alone the distance.
Maybe the next step is to build a boat that is designed just for the Murray Marathon, the only way to go faster is a longer narrower boat. Maybe a 10-12m long boat that bolts together in the middle. Anyway you have a year to design and build it, unfortunatley you will be a year older!

Ian

Ian
Not hard to come second in the division because there were only two boats classified UNR1 OV50. The other guy just happened to be the overall winner in the Full-distance Open. I was happy with 14th out of the 69 starters.

His boat is boat #16. It is the very long boat in the foreground of the photo at the start of Day1. My estimate is that it is well over 7m long and would suit his weight and power. It is not a conventional kayak as it is longer than any standard kayak for single paddler that I know of - hence the unrestricted classification. It is not a surf ski.

The length of V14 is close to the lowest drag for my weight and power level. The best way for me to go faster is to get the weight even lower and get rid of the shaft strut. The success of the folding prop enables both of these possibilities.

I have attached an image of a boat I am working on for my sister. If it works out well I will build a slightly longer version for me. The hull will be almost identical to V14 but it will have the drive and seat integrated with the hull. Should also reduce windage.

Rick

[Guest625101138]

Originally Posted by Leo Lazauskas

Great effort and a lovely report, Rick.
Next year, shave your head and glue your ears back. Every little bit helps!

Leo.

Leo
A good deal of my gratitude goes to you for Michlet/Godzilla. It is satisfying to know that I am close to the optimum hull. I have a sense of satisfaction when others complain about my boat being lousy for drafting.

I have little doubt that the flat bottom of this V14 hull (constrained chine) is better than the "optimum" rounded chine V12 hull (no chine constraint). There is a slight weight advantage with V14 being shorter but even in the 10 to 11kph range I am getting a little lift rather sinkage. At higher speeds I do not have to work particularly hard to leave all the paddlers at the start. No doubt legs are better than arms for power but my start group had a couple of young and fit guys in very light/fast racing kayaks. (They nick-named me Lance for my fast starts)

I am glad you enjoyed the report.

Rick

[I57]

Don't knock the place Rick, 2nd is 2nd, they don't have to know the number in the group. Problem with 10 year age groups is the big difference between a 50 year old and a 59 year old, thats why in Masters Athletics they have 5 year age groups.
Design for boat looks interesting, biggest challenge will be getting the weight down. As you have said previously V14 is almost at optimum design, its either reduce weight or look for an entirely different approach ( maybe someone out there has some ideas).

Ian

[Guest625101138]

Originally Posted by OldNick

......
OOI, did the overall winner win on handicap, or outright?

Nick

Nick
It takes quite a bit to get through the results.

The toughest race is full-distance. There are half distances and even shorter for Juniors.

The toughest way to compete is as a single person. Followed by single crew, and then relay.

As far as I can tell there were two boats faster in actual speed than Tony Hystek's 13.6kph. One was a two person recreational kayak with the same crew. The class has a length limit of 7.5m. The two OV40 guys averaged 13.8kph. The other boat was a K4 that operated with crew relay. It averaged 14.1kph but was not as fast as the K4s in previous years. It would have crew of 4 at any time and 16 to 20 people in the team. Hence you would expect it to go fast. There was a K1 in the open category (no age allowance) who equalled Tony's speed.

Tony would have been maintaining about 12kph through the water for the entire time. That is quite impressive for anyone let alone a 53yo. I need to get a lot smarter and a bit fitter to beat that.

Rick

[Leo Lazauskas]

Originally Posted by Rick Willoughby

They nick-named me Lance for my fast starts

We saw the photos and we know why they named you that!

I'm not sure if you can squeeze much better performance out of the
hull design, but maybe adding a small amount of form drag will help
your predictions. If you don't believe in form factors then ignore
what follows

For rowing singles and doubles, Scragg and Nelson found a
form factor that could be applied to the (empirical)
1957 ITTC skin-friction formula. Their factor is:

1+k_f = 1 + 0.0044 *(a_in + a_out)

where a_in and a_out are the entrance and exit
half angles in degrees.

I have also used Prohaska plots to convert their experimental
data so a factor can be used in conjunction with Grigson's
skin-friction formula. In that case:

1+k_f = 1.0289 + 0.0015*(a_in + a_out)

These factors are only available in my personal version of
Godzilla, but you can add the form drag after finding several
candidate hulls to see if it changes their ranking. I'm guessing it
won't gain you much more that 1%.

Good luck!
Leo.

[Dennis A]

Murray Marathon

Well done Rick

Both you and your boat have achieved a excellent performance.
With regard to that troublesome weed on the shaft strut, could you not build the curved shaft into a small skeg that is about 125 mm deep beneth the hull and angled at 10 to 15 degrees, or would this increase the drag to much.
I was also interested in your comments on flat bottoms and lift.
I have found that lift can be increased by setting the boat to float with the hull laying at 2 to 3 degrees up at the bow.
On my 16 Ft Flat bottomed boat that I am at present building, I am using a square stern to create maximum lift in the hope that the surface in contact with the water will be reduced.

Dennis

[Guest625101138]

Dennis
I am going to try without a strut, which works OK going forward.

A little rake on the strut to force leaves up rather than down should work for leaves but there is also curled bark and longer weed that will build up on the strut irrespective of the rake.

My V14 hull has some rocker and flat bottom sections. At rest it sits on its lines but there is enough rocker and flat surface at the bow to give it slightly bow up at higher speed. I have not measure the lift or inclination but I can notice it in the speed compared with round bottom hull.

Flat transoms are interesting because they tend to squat first before providing lift. The water under the hull accelerates to the free surface and this higher velocity lowers the pressure under the transom and it sits lower. So you get more bow up but at the cost of the stern sinking deeper.

Rick W

[Leo Lazauskas]

Originally Posted by Rick Willoughby

My V14 hull has some rocker and flat bottom sections. At rest it sits on its lines but there is enough rocker and flat surface at the bow to give it slightly bow up at higher speed. I have not measure the lift or inclination but I can notice it in the speed compared with round bottom hull.

Flat transoms are interesting because they tend to squat first before providing lift. The water under the hull accelerates to the free surface and this higher velocity lowers the pressure under the transom and it sits lower. So you get more bow up but at the cost of the stern sinking deeper.

If you are willing to send me the offsets etc of the V14 of your central hull I will calculate the sinkage, trim, and the sinkage force and trimming moment for a range of speeds.

However, I will need offsets above the static waterline so Flotilla can use true offsets rather than assuming that the hull has vertical sides above the waterplane.

Leo.

[Guest625101138]

Leo
It will be a very interesting result for me. I feel I am starting to get lift above 3.5m/s. I have never taken it to full power because the folding prop has light blades but I have got to about 4.7m/s.

See if the attached offsets from Delftship makes sense. It is as a very simple hull form made from 4 flat panels per attached image. The sides flare slightly.

Rick

[OldNick]

Gee Rick that boat for your sister is starting to look like an F1! You need to make the ama arms in a wing shape now!

I assume that integrating the shaft into the hull will remove or lessen the problems with a free shaft and no skeg. Since you talked of a lighter prop (remember the logs and rocks!) I was wondering if you could surround the shaft with a foam and composite sheath, actually attached to the shaft, so that the shaft tended to float more when stationary. I know it's more drag but it may solve a problem.

Nick

[Guest625101138]

Nick
The main problem I have had with unsupported shafts is having them hit the hull in a turn and taking chunks out of the hull. By mounting the prop aft of the hull it can move about freely. The shaft is spring steel and will take a heap of abuse. With the prop unconstrained it will easily bounce off rocks or logs.

The prop will be lighter but I expect it to be higher strength for weight with aluminium alloy blades and solid HDPE or nylon hub.

Attached has a bit more detail on the new design.

Rick

[portacruise]

Thanks for the interesting report and pictures, Rick. Good information for us on an extended, rugged test of the folding prop and shaft. You indicated the finish was done with a fixed blade prop, so at least you have good data for improvement on the folder if it was jammed, damaged or lost. The folder is appearing to be an important breakthrough, as I had thought.

Running without a strut would seem to be the way to go, as you have indicated. That's the way I've minimized weed problems in my low power unit. For reverse, an on board paddle is not glamorous, but eventually gets the job done. Another possibility might be some kind of retractable hook that could deployed ONLY as needed to keep the prop from diving when doing reverse or when beaching.

I ran across this torsion capable CF tube when looking for ways to further lighten my drive shaft:

http://dragonplate.com/ecart/product...ID=4107&cID=79

It is overkill in my application, but possibly HPB capable, maybe in one of the larger diameters.

Congrats on a good run. I'm sure your design improvements by next year will put the young wippersnappers on notice.

Vic

Porta

Originally Posted by Rick Willoughby

Attachment 39120I am back from my 2009 tilt at the Murray. I wrote the attached report for future reference while my memory of the race was still clear.

The folding prop was a great success and it has potential to underpin further design evolution that overcomes fouling problems with the shaft strut.

Rick

[Guest625101138]

Vic
I have been thinking along the same lines with the hook. At least for easy transport to stop the prop from bouncing about.

For reverse it is not a big deal to use my hands. I can get 3 to 4kph just by paddling with my hands. In the temperature up there I try to stay wet all the time to get the evaporative cooling.

I am thinking of trying to diagonally wrap an aluminium shaft with fibreglass tape or CF tape to get some bendy but good in torsion. The CF tube pictured does not seem to have any diagonal strands. It is close to the right size and price is reasonably so could be worth a look. I wonder if they have actually measured the torsional compliance?

Rudders and prop now added. With building it was as easy as drawing it.

Rick

[Leo Lazauskas]

Originally Posted by Rick Willoughby

See if the attached offsets from Delftship makes sense. It is as a very simple hull form made from 4 flat panels per attached image. The sides flare slightly.
Rick

No luck, Rick. Delftship gives me a mess at the top of the hull and holes in the bottom.

Instead, maybe you could produce a Michlet file from your Delftship fbm. Temporarily set the draft high so the file contains waterlines above the static waterline.

Leo.

[Guest625101138]

Leo
Here is the .mlt file. The draft is set to 130mm. The design draft is 97mm. That is where I am when light.

Most testing is done in a freshwater lake with depth from 5 to 15m. Temperature up to about 15C this time of year.

Rick