20ft Nemesis Cat

I think I would be sworn at if I drew up a tunnel cross section like that over here in SA hahaha. That is also a very wide beam compared to the length overall of boat wow.

 

Yes, it is high, if not totally dry.

 

Majority of launches over here occur on the beach hence the boats are mostly of the small cat range. These boats take some serious beating in the big surf we get. We have breakneck trailers which tilt and drop the boat off on the sand then a tractor pushes the boat off with a long pole. You'll see on the Seacat a stainless bracket where the pole fits in.

 

I have actually only seen one cat like those SA ones in Australia, they are built in alloy. The quite narrow tunnel is obvious.

 

There is nothing better anywhere, in that boat length, despite it being 45 years old design. They would run on 2 x 70 at a cruise of 20 knots, 2 x 90 would give 25 knot cruise in quite nasty conditions even, a few people went overboard and put as much as 2 x 175 on them. Didn't make them unsafe, just fuel guzzlers. The larger 700 series (23-24 feet) was a much bigger boat, but a lot of people thought the smaller boat was better.

 

@Mr Efficiency I don't understand the wide flat tunnel theory of that drawing you posted, the only good things on that hull that I cant take out of it is nice high tunnel clearance and the slender hulls otherwise the wide flat tunnel to me seems like a big area for waves to slap against and create an uncomfortable ride??

 

These Noosa Cats are based off the Shark Cat hey? They seem to have fairly fat demi-hulls.

 

I am merely reproducing what I know the dimensions to be, I spoke to a fellow who had extensive experience with a variety of power cats from 16 to 35 feet, and told me the Sharkcat 560 was the most "forgiving" of all of them , the last I heard he was rebuilding a rare centre console model for his own use, the ride is very good, the only time I felt it wasn't as good as I would like, was quartering a short steep chop, but I can only recall two occasions that occurred.

 

Noosacat is a continuation of the Sharkcat line, I don't think the hulls on their product could be called "fat".

 

Ok no, then it's just the angle of the picture making them look fat.

 

I think a partial explanation for the SA "fat" demihull preference, would be it makes for less draft, those old 18 footer drew about 20" hull only, that is no asset with beach launches.

 

Two more designs that I find interesting very popular and worth taking a look at are the Hammercat 35 and the Freeman 37, would you call these fat demi-hull cousins or more the slender hull type. I haven't seen a Freeman in person to comment on the chine beams but I walked around a Hammercat on the dock which has quite a unique design approach and styling. These boats have a very different tunnel shape compared to the SharkCat 560, unfortunately I haven't fished off any of them to have comments and this is taking away on the size differences, just merely looking at shapes, height and width.

Freeman 37.





Hammercat 35'

 

Wow, they must have tank tested the crap outta that hammercat to come up with that hull shape.

The transom dr looks to be uneven with more angle in than out which would promote more stability at rest while still allowing for good cutting.

The third or second chine I guess is one heckuva splash rail; stop you from pitchin in.

The Freeman shows that same super high entry at the bow as I noted a difference in the others.

I am fond of the lines of the Freeman 37 and have drooled over them before.

 

Obviously the Freeman is a big boat with a not overly wide overall beam, and running two big outboards each side more or less mandates wide demihulls. It does appear to me that the SA boats are wide and relatively flat aft, and that would suit beach launchings better, as I say am 18 foot boat that draws 20" with the outboards tilted up, is at least 6" deeper than a vee-hull, and with twin outboards on both types, you are almost talking a foot of additional draft trying to negotiate shallows. Little wonder cats are seldom seen at beach launch areas over here. So I would say there has been evolutionary pressure toward the fatter hulled boat in SA, with the beach launching requirement. I think the degree of vee you have with the Nemesis Cat, is working against that to a degree, that is increasing draft. I also think that unless you use wide-ish chine flats, you could encounter some porpoising. And that is not something easy to get rid of with cats, finding a place to fit tabs is the problem.

 

If it wasn't for one singular "vice", the Sharkcat 560 would have continued to sell like "hot cakes", as they did in the first few years, on the strength of vastly superior sea handling, than similarly powered monohulls, and that vice was a way of destroying outboard motors, through the ingestion of a fine mist that gathered around the back of the boat, drawn into the crankcase of two-strokes, it greatly shortened engine life. With four strokes today, that appears less of a problem, and combined with better fuel use, there is a revival of interest in restoring and re-powering them. One attempted remedy to the salt mist, was to seal the engine cowls, and run long hoses, like over-sized vacuum cleaner suction hose, into the cabin of the boat. It did not seem to gain a great deal of up-take, possibly because of a fire/explosion risk.