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The new compmillennia 39 cat

Old 05-17-2016, 06:01 AM
  #1221  
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Originally Posted by pas View Post
I am thinking of staying with my same Yanmar 6LP's just using a turned up version. They will easily make 350 hp and loads more torque. I really like the FPT but I think it is overkill for me. And no to Arnesons, XPower drives are where its at, unless the boat will be kept in the water, then Arnesons are a good option.
Originally Posted by Otseg View Post
One challenge with Jassby's project is that he wishes to maintain a 12' beam for regular over the road trailering. I would prefer to go to 14' beam and if it was a quad fish boat we suggest that. On the other hand, no doubt Jassby's will be a 100 mph boat so keeping the frontal area down is a help.

Cruising past his Nortech buddies is forever on his mind.

Much like the quads, I don't see how diesels can fit in the narrow sponsons. You talk of increasing beam, I'm assuming this comes with a scaled sponson width?

Originally Posted by Jassman View Post
Thats ok ....Mako's got it covered..
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Old 05-17-2016, 06:56 AM
  #1222  
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11'11" is cheaper to trailer than 12'.
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Old 05-17-2016, 06:59 AM
  #1223  
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Originally Posted by MakoMyDay View Post
Much like the quads, I don't see how diesels can fit in the narrow sponsons. You talk of increasing beam, I'm assuming this comes with a scaled sponson width?


And I assume that a the heavier engine weight and wider sponson would also kill any efficiency gains with diesels over outboards, not mentioning the cost.
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Old 05-17-2016, 11:25 AM
  #1224  
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f diesels, what will it do with a pair of 200 lean burns.
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Old 05-17-2016, 03:12 PM
  #1225  
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Originally Posted by Coquille View Post
f diesels, what will it do with a pair of 200 lean burns.
Yes how good is the mileage if you power down and take off more weight?
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Old 05-17-2016, 04:02 PM
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Originally Posted by catfoiler View Post
Yes how good is the mileage if you power down and take off more weight?
Jim has stated that Hull#2 will be 1000 lbs lighter and could take Twin 250's. So its not hard to do that math.
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Old 05-17-2016, 06:33 PM
  #1227  
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Originally Posted by MakoMyDay View Post
Much like the quads, I don't see how diesels can fit in the narrow sponsons. You talk of increasing beam, I'm assuming this comes with a scaled sponson width?
Originally Posted by Bullshipper View Post
And I assume that a the heavier engine weight and wider sponson would also kill any efficiency gains with diesels over outboards, not mentioning the cost.
For the quads (not Jazzman's) and diesels, yes the hull from the tunnel out is wider by 12"

In planing hulls, short and wide is more efficient than long and narrow. This is where stepped hulls gain efficiency. Two shorter and wider planing surfaces are more efficient than one long and skinny one. Making our hulls wider will not cause us to lose efficiency.

We found that we gained fuel economy the faster we went, up to about 1.9 @ 55 mph, then it dropped to 1.2 @ 68 to 70 mph.

I think this was partly our hull design and construction, and partly about the "sport mode" prop optimized for top end. On order are the "Fish Mode" props, less pitch, big area blades optimized for mid range. Do we get a second case of beer if we hit 2.2 mpg @ 45 mph?
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Old 05-17-2016, 06:35 PM
  #1228  
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Originally Posted by Coquille View Post
f diesels, what will it do with a pair of 200 lean burns.
don't know what a "lean burn" is but nothing burning gasoline will ever beat a diesel for mpg. comparing similar HP and drive trains (no shafts). Also in addition to getting 50% better (or more) the fuel actually costs a lot less so your $/mile costs are less than half of a gas powered boat. I paid $2.30/gal for diesel on the water over the weekend, gas was $4.20!

Jim had suggested a pair of Steyr diesels the most powerful one is almost 300 hp, a set of those paired with a Blackhawk surface drive I think would be 3+ mpg at any speed where the Verados get 2 mpg. Top end would be in the 60's.
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Old 05-17-2016, 06:41 PM
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Originally Posted by pas View Post
don't know what a "lean burn" is but nothing burning gasoline will ever beat a diesel for mpg. comparing similar HP and drive trains (no shafts). Also in addition to getting 50% better (or more) the fuel actually costs a lot less so your $/mile costs are less than half of a gas powered boat. I paid $2.30/gal for diesel on the water over the weekend, gas was $4.20!

Jim had suggested a pair of Steyr diesels the most powerful one is almost 300 hp, a set of those paired with a Blackhawk surface drive I think would be 3+ mpg at any speed where the Verados get 2 mpg. Top end would be in the 60's.
3 mpg is very appealing, trying to justify the upfront cost is where the problems arise.
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Old 05-17-2016, 07:56 PM
  #1230  
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Believe me I understand, I love the Yanmars I have now and would love to do diesels again, but 2 mpg is pretty damn good and 7 year warranty is not bad either. But you end up with a much nicer looking boat, and a lot more usable space with diesels. I think part of the upfront cost justification is that when selling you get some of that back. Also even though it would get 3+ mpg in terms of cost it is the same as getting 4+ mpg compared to gas power that gets 2 mpg. We will see I am leaning toward diesels but still undecided.

The other problem is that you need an inline 6 diesel to work in this boat, so you are limited to the Steyr lineup, Yanmar 6LP (not really sold new anymore), FPT 570 (awesome but to big), Cummins 550 (also awesome and even bigger) and I think that is it. And stepping up to the FPT or Cummins adds at least $60,000 in drivetrain alone, over smaller engines that can use Bravo or similar outdrives.
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Old 05-18-2016, 05:38 AM
  #1231  
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Originally Posted by pas View Post
Believe me I understand, I love the Yanmars I have now and would love to do diesels again, but 2 mpg is pretty damn good and 7 year warranty is not bad either. But you end up with a much nicer looking boat, and a lot more usable space with diesels. I think part of the upfront cost justification is that when selling you get some of that back. Also even though it would get 3+ mpg in terms of cost it is the same as getting 4+ mpg compared to gas power that gets 2 mpg. We will see I am leaning toward diesels but still undecided.

The other problem is that you need an inline 6 diesel to work in this boat, so you are limited to the Steyr lineup, Yanmar 6LP (not really sold new anymore), FPT 570 (awesome but to big), Cummins 550 (also awesome and even bigger) and I think that is it. And stepping up to the FPT or Cummins adds at least $60,000 in drivetrain alone, over smaller engines that can use Bravo or similar outdrives.
Diesel is more in California and Arizona, last time I checked. Paid $1.40 for regular last week. And I seriously doubt you will get 50% more mpg in a cat that is sensitive to weight as I have a freind here with a 28' Prokat with 2 little yanmars that barely fit and his top end is around 24 mph. 17 knots is his sweet spot. These hulls do 45 with outboards.
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Old 05-18-2016, 05:42 AM
  #1232  
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Its hard to understand why the small marine diesels are so expensive. I was looking for diesels for my 22 cat and some other projects and came to the conclusion that I should buy a pair of VW EOS diesel cars with the 2.0 liter I4 engines. I figured I could part out the rest of the brand new car on EBAY and probably net more than I paid and effectively get my Cat engines free!
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Old 05-18-2016, 06:04 AM
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Originally Posted by Otseg View Post
Its hard to understand why the small marine diesels are so expensive. I was looking for diesels for my 22 cat and some other projects and came to the conclusion that I should buy a pair of VW EOS diesel cars with the 2.0 liter I4 engines. I figured I could part out the rest of the brand new car on EBAY and probably net more than I paid and effectively get my Cat engines free!
https://www.mercurymarine.com/en/us/...el/20l-tier-3/

Funny enough, that is the same basic 2.0 TDI engine that would be found in a VW Eos TDI. I think all versions come in more expensive than what the highest trim VW 2.0 TDI cost. Obviously you are also getting a drive, some marinization and the option for a higher hp tune...
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Old 05-18-2016, 07:56 AM
  #1234  
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Originally Posted by Pettit Marine Paint View Post
https://www.mercurymarine.com/en/us/...el/20l-tier-3/

Funny enough, that is the same basic 2.0 TDI engine that would be found in a VW Eos TDI. I think all versions come in more expensive than what the highest trim VW 2.0 TDI cost. Obviously you are also getting a drive, some marinization and the option for a higher hp tune...
are all the internals the same?
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Old 05-18-2016, 08:17 AM
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Originally Posted by midcap View Post
are all the internals the same?
Can't say, I just know that VW and Mercruiser entered an agreement a few years ago.
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Old 05-18-2016, 01:03 PM
  #1236  
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They have some small inline diesels as well

http://www.hyundai-seasall.com/html/main/?Lang=
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Old 05-18-2016, 01:48 PM
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Serious question...how about a pair of these:

http://www.oxe-diesel.com/
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Old 05-18-2016, 02:56 PM
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I don't think you need the big hp Diesels in the Compmillennia Cat you might think.
If you had a pair of 258, 279, or 292 hp Styer's installed you would only need to pull 200 hp from each engine to go 48 mph. That is roughly 3,000 RPM and which is very close to both peak torque and lowest specific fuel consumption per hp. Very, Very efficient.
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Old 05-18-2016, 03:33 PM
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The Perkins line in Mexico were the best deal I could find 15 years ago. 4 cyl were only about 6K if I remember right. But I do think they were naturally aspirated. Thes parts for these are also very reassonable.

No one will touch the Yanmars here.
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Old 05-18-2016, 04:39 PM
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I just finished reading 31 pages of posts over the past 3 days. As a new cat owner (less than 1/2 a season), I have completely converted. Reading your post has kept me up at night dreaming about what could be in the future.

My question is, could a cat be built to compete with the likes of Jarrett Bay / Viking / Etc. in the Sportfishing world?
Being in NC, this is all I see. My wife's Uncle has an amazing Jarrett Bay, it rides great... but I would love nothing more than to pull up (and hopefully pass them) in my Sportfishing Cat.

Why would someone not want to own/build a cat like this? What am I missing? What would be the negatives?

I have not made my millions yet, but when I do, I would love nothing more than to build a dream boat too. (Please post the future builds for inspiration!)

When I do a web search these are the photos I found.
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