Water Rat Developments

My customer and friend, Ross Trinder from Toowoomba, Australia, has just launched the very first (to my knowledge 10.8 ft length Water Rat. Prior to this there had been a number of the original 9 footer on the water, but Ross is the first 10.8 ft version.

Ross Trinders Water Rat 10.8 racked on top of his Green Island 15

Jon Trinder, at 6 2", gives some proportion to the boat.

Jon seems a big fellow, but the 10.8 version sits high in the water

Ross and Jon Trinder elected to instal a commercial seat

Ross Trinders beautifully finished Water Rat 10.8

Al Burke has written a couple of nice pieces for Duckworks about his Water Rat here (scroll down to Water Rat) and here (again, scroll down to Water Rat).

Als Water Rat showing that even the short version can carry a load

Als wife, Rhonda, showing that the tumble home topsides make paddling easy even though the boat is wide. She is also showing that though Al is an expert pilot as well as waterman, she is better looking than him....

As you can see Al Burke did a top-class job of this Water Rat

Here is a photo of my youngest son, Steve (a long time ago), showing how stable the very first boat was. She was originally designed by my great friend, Doug Laver - I collaborated with the project, but the idea was Dougs and I still call her his design. Since the original, Ive worked over the projections and some of the proportions, but as much as possible Ive stayed true to Dougs original concept and shape.

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Water Rat

Edward has written in regard to the discussion about flat-bottomed hulls: -

Hello, There was a flat bottom sharpie built in England in 1898. Very unusual at the time. She was 14ft and had a sprit main and jib. Mr. Lillistone could you look at this picture of her from Dixon Kemp, and comment on what you think? Id quite like to build an historical replica to see how she went (fast by all accounts at the time as she was banned from racing). https://picasaweb.google.com/lh/photo/OYrhbqLKYyB9iQF9G3RN3HY6h4w9_WFXdAPmTale1U0?feat=directlink Regards Edward

Thanks for the comment and the drawing, Edward. I am flattered that you are interested in what I have to say, but I am mildly worried that people may think that I know more than I actually do!

Anyway, here is my opinion, and Id welcome input from others who may have a deeper understanding of the subject.

I view this boat in two separate parts - the forward sections and the aft sections. She is quite wide for her length, which immediately introduces problems with eddying around the chine. The line of the chine is very flat up forard, which also increases the problem of wild eddys forming around the chine, causing drag and wild steering.

However, the chine line in the aft sections shows a nice lift when viewed in the body plan, and I think it comes close to the optimum when hoping to prevent eddying. If you look closely in the body plan (i.e. the end elevation) you can see that the line of the chine more-or-less bisects the angle between the bottom and the topside panels.

So, I think that this boat would perform well as long as she was sailed flat with the fore-foot lifted clear of the water - which she would naturally do considering her large sail area and tucked-up transom. Her shape looks similar to plenty of racing dinghies from the last forty or fifty years. If built lightly, I think she would go rapidly, but I also think she would be a handful in a decent breeze.

The potential for the chine at the bow to produce turbulence would not be a problem when running fast and level in flat water, but if she stuck her bow into the back of a wave (especially running down-wind) I think she could sheer off wildly and suddenly.

That is my opinion, but just remember that there is no guarantee that I have any idea about what Im saying!

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Water Rat in 4mm Plywood Sailing Version

Water Rat is a 3 foot wide plywood kayak which can be built with a length of either 9 or 1010". This boat has an unusual, but attractive shape, and has proved to be quite popular. She was initially drawn by my friend Doug Laver back in the days when we were working at my workshop in Brisbane, and we had started experimenting with Gregg Carlsons Hull Designer program.The plans that Doug and I used originally were very difficult to interpret when it came to the shape of the developed panel sections, and I subsequently redrew them in a CAD program, incorporating a few variations and conventional dimensioning. You can read about the boat in a previous post here:-    http://rosslillistonewoodenboat.blogspot.com.au/2011/11/water-rat-developments.html

Dougs original Water Rat with my son, Steven, showing off the boats stability. Steve was about 12 then, and I havent seen this activity performed by an adult - but for a canoe she is a very stable boat.

Ross Trinder, from Toowoomba in Queensland, Australia, has built a number of boats recently including a Green Island 15, one of my First Mates, and a Water Rat. My good friend Al Burke also built a Water Rat, but used 4mm plywood instead of the 6mm plywood specified. Al applied some strategic stiffening materials and as you can see in the comments, his boat weighed in at 17 kg.

Ross Trinder is now building a second Water Rat, and this time he also is using 4 mm ply. Another variation on the theme being experimented with by Geoff Leedham in his boatbuilding program at a school in Alice Springs, Outback Australia, is to use 4 mm plywood for the entire boat with the exception of the bottom panel, which is made from 6 mm plywood.

This boat is a very simple project which involves very little time and very little money. However, it represents a great way to gain experience in the use of  epoxy and plywood, and the resulting boat is great fun to use, is very stable, and is surprisingly seaworthy in protected waters.

Ross Trinder has asked me whether it would be practical to fit Water Rat with a sailing rig. Given that she is 3 feet wide and carries her breadth out into the bow and the stern, I think that she would be able to carry sail reasonably well, and the only real challenge is to decide how best to give her some lateral plane. My first reaction is to make use of the leeboard, but Im beginning to think that an off centre dagger board would suit the boat very well. I will be doing some preliminary drawings shortly, and will post them here.

In the meantime, here are some photographs of the early stages of construction of Ross Trinders 4 mm Water Rat. You can also see Al Burkes finished 4 mm version via the link at the end of the first paragraph.

In this photograph the panels and bulkheads have been cut out accurately, have had holes drilled along the edges of the panels, and the boat assembled using plastic cable ties. After having ensured that there is no twist in the boat, Ross has placed a series of short tabs of thickened epoxy between the cable ties in the forward and middle sections of the boat.

Here you can see how the "tack-welds"of thickened epoxy remain clear of the cable ties, and are very small in cross-section. After the epoxy has cured, the cable ties will be removed and a larger fillets of thickened epoxy will be applied in a continuous run over the top of the "tack-welds" and have glass tapes laid over them while still wet.

Note how the bow and stern transoms, and the bulkheads, have centrelines marked. These are lined up with the centreline on the bottom panel, and as long as there is no twist allowed, the boat must come out the correct shape - even though there is no strong-back or mold.

Here you can get a good idea of the shape of the boat, and as long as the panels are cut out accurately, the shape of the boat is smooth and fair. This particular boat goes together very easily, and it may be possible to get away with as few as half of the cable ties you see in the photo.

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