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Random Quote: CAPT TO CREW--I DON'T KNOW WHERE WE ARE,,BUT WE ARE MAKING darn GOOD TIME.
Here in the land of the poor, the panga is king due to is low cost and light weight for beach landings and launchings by hand.
The passengers sit in the low deadrise stern, and let the bow bounce around, parting the waves to make a wake and a smoother ride with good economy.
These boats average 22 to 26 feet, and the law requires them to use a motor up to 75 hp if they want to qualify for federal funding.
A lot of these fellows will just put a 50-75 hp 4 stroke Mercury or Yammy, keep their gear, gas and weight to a minimum, and will top out at 30 mph WOT, burning 6-12 gallons in a whole day of billfish trolling running 10 to 20 miles offshore.
The secret is an extra large light hull that drafts next to nothing getting great fuel economy, yielding lots of room, and the capacity to add a lot of weight when needed.
When I designed my cat, I figured I needed a 21 for space requirements, then went to a 24 to cut the draft and the calcs demonstrate that my speed and economy will improve with the same engines. The hull is fairly cheap compared to the motors on a per year cost, so I think that more boat less motor is a good strategy.
With motors my hulls at about 4500lbs.. It'll run 36 mph +/- 1 mph depending on conditions(with bottom paint)
The Alloy cat that was shown on here a month or so ago, that was built in Texas(?), and had the 150's was pushing 50+ mph(I think, my memories fading like everything else)
What I think, is that I'm wondering if this is the type of thinking your interested in
How do you keep this cat boat from being squirrelly when running with a light load?
Can you make a hull design that allows you to fully load the cat and not have a significant change in its running characteristics?
What kind of operating efficiency benchmarks are you hoping to achieve? (gph, mpg, idle speed, WAFO speed, amps, co2 lbs per hr, septic capacity, etc)
Will there be a vanity mirror in the head?
Can you make a slipper locker in the CC?
Can you add a Money Meter next to the Hour Meter? The money meter is intended to provide a constant read out of how much money the boat has consumed in a real time format.
Do you plan on mounting the batteries directly to the exterior of the transom for ease of service?
What I am trying to piece together in my mind are a few design variables like
There is no substitute for length to improve ride and doing it in a cat is even more effective.
Go longer with a little flatter deadrise to increase speed, gas economy, get less draft to skim over the waves to reduce wave resistance when pushing water.
21 foot cat has 17 feet of hull in water, where 24' has 20 feet weighing 250 lbs more hull weight against 1100 lbs of additional bouyancy.
Twin 75 's giving you 30 mph cruise on longer more boyant hull at 6 mpg, against 150's with 40 mph cruise at 3 mpg.
Having more room for the odd day that everyone wants to pile in and go for a ride.
The extra 3 feet costs about 2400 dollars, but saves you more than that in motors, and cuts your operating cost in half.
etc, etc.
You know man you're just going to have to bite the bullet, fire up the mig rig and build one of these to know for sure. Your design is solid, well thought out.
No, my cat doesn't run 50 mph with 150's but it does crank out a respectable 41 all out with twin 150's. The big news is fuel mileage though, it's easy to cruise in the lower 30's at 3.5 mpg. Interestingly enough, it doesn't seem to make any difference in top end or fuel burn what load is carried. I'm thinking that if there are sufficient planing surfaces that speed and fuel burn are more related to hull drag than weight. Course those planing surfaces are going to carry a ride penalty, nothing would ride so smooth as a slightly knife blade sliding through the water.
No, my cat doesn't run 50 mph with 150's but it does crank out a respectable 41 all out with twin 150's. The big news is fuel mileage though, it's easy to cruise in the lower 30's at 3.5 mpg. Interestingly enough, it doesn't seem to make any difference in top end or fuel burn what load is carried. I'm thinking that if there are sufficient planing surfaces that speed and fuel burn are more related to hull drag than weight. Course those planing surfaces are going to carry a ride penalty, nothing would ride so smooth as a slightly knife blade sliding through the water.
Chuck
Right on Chuck, but you have a cabin and are over 28 feet long, have a lot more wind drag, so your numbers are still pretty darn fantastic, and what I have designed has come in at 100 lbs a foot x 24' even after beefing it up. Are you close to this lbs/foot for the dry hull no mootors?
Hull drag is something I forgot about. As I remember you did a lot of sanding on your hull when building.
Is there any way to get it nice and smooth like gel coat, then make it nasty slippy with wax or some other filler?
Are your motors as high as you can get them to reduce lower unit drag?
Fyi, you are getting better mpg than the TV26's, and they are very light for their size.
How do you keep this cat boat from being squirrelly when running with a light load?
Can you make a hull design that allows you to fully load the cat and not have a significant change in its running characteristics?
What kind of operating efficiency benchmarks are you hoping to achieve? (gph, mpg, idle speed, WAFO speed, amps, co2 lbs per hr, septic capacity, etc)
Dave,
When you plane in your fountain or any monohull, 1/2 of the boat's length comes out of the water, and this unsupported overhanging weight makes it more squirelly at speed, where the cats tend to run a lot more parrallel and imersed.
All cats are said to be trim sensitive, but I think that this is less true if you purposely make them longer and more bouyant, which is also a prime factor to increasing gas economy, which isn't really that important, but is a factor.
As far as running speeds, I really think it is hard to keep the boat from launching in 2-3's when exceeding
35 mph at 4000 rpm and 4 mpg, so I look at this as a practical cruise speed, and 45 mph when its smooth at 3 mpg.
With motors my hulls at about 4500lbs.. It'll run 36 mph +/- 1 mph depending on conditions(with bottom paint)
The Alloy cat that was shown on here a month or so ago, that was built in Texas(?), and had the 150's was pushing 50+ mph(I think, my memories fading like everything else)
What I think, is that I'm wondering if this is the type of thinking your interested in
And that boat from Texas had to be at least 30 feet long with real wide bouyant sponsons. Said he was getting 54 with bad props on his maiden run, so not bad for twin 150's.
36 mph on a 90's on a 24 with a cabin is also pretty darn good too. I was thinking 140's for my hull but I may be overdoing it as I will only weigh 3200 rigged with 4s, or abot 3000 lbs with 2S power. My sponsons have only 13 degrees of deadrise at the transom,so I would guess that this is less than yours, and a lot more efficient than the semi displacement hulls that defy imagination, and really only serve to release easier in tall molds IMO.
You know man you're just going to have to bite the bullet, fire up the mig rig and build one of these to know for sure. Your design is solid, well thought out.
Chuck
I think I have finally found a shop that is cheap and competent in town. You suggested that I could save using 5052 over 5083, and I would like to go this route on the prototype. Any sources for this material that you know of?
I decided that I am going to sell the Cape Horn, and just use the little Seaswirl for local bass fishing close to home while I get my new business of the ground, and build the cat.
Hey BS, give Jay a call at black lab he would prob help locate the alloy.
__________________ F350 4x4/ Dodge 2500HD 5.9L Cummins
Leaving the Picture of the Ford cuz I miss it
Pacific 2325 cc
Honda bf225
aluminumalloyboats.com
Hey BS, give Jay a call at black lab he would prob help locate the alloy.
-----
welder
Thanks welder but Blacklab just uses 5083, which is more expensive. I need 8 X 24' sheets laser cut in metric thicknesses, so this is not an easy question.
Bullshipper
What part of mexico are you located ?
San Luis Potosi, San Luis Potosi- the Denver of Mexico
__________________ F350 4x4/ Dodge 2500HD 5.9L Cummins
Leaving the Picture of the Ford cuz I miss it
Pacific 2325 cc
Honda bf225
aluminumalloyboats.com
Mexican Boat Trick 
photob
ucket.com 
