Hi, I was asking Mark if his boat had single or twin engines since his numbers differed so much from yours and seemed unrealistic for a single engine boat... "cupping " a prop is giving a little flare to the edge of the prop and acts like having extra pitch, as far as speed, a boats efficiency is best at or bellow hull speed, since you had a small boat you could feel that bellow lets say 5 knots, the boat moved very easily, but to get up on plane you had to gas it, the boats stern would go down and kind of dig in untill you gave it enough power to climb on top of the water and break free... basically what is happening is that as you go faster, the water does not have time to fill the hole the boat has created, so the boat kind of sinks in the hole unless you have enough power to break free and plane above the water. the theory is 1.37 X square root of the water line length = your hull speed. most power boats are planning or semi planning hulls, most sailboats are displacement hulls, you can put 1000 hp in a 30 ft sailboat and all it will do is create a big hole it keeps on trying to get out of... if your water line length is 24ft, your hull speed is 6.7 knots... to adapt to marine use, you will need a SAE bell housing, I believe cummins uses a #2 on their engines, fairly readily availlable at semi wrecking yards, the bell housing off a 4bt works as well, a lot of industrial equipment like gradals, skytrax and extended reach fork lifts use 4bt's. I do believe someone make an adapter to use the dodge bell housing... Eric
----- Original Message ----- From: dodgetkboy78<mailto:[email protected]> To: UnifliteWorld<mailto:[email protected]> Sent: Friday, September 11, 2009 8:45 AM Subject: [UnifliteWorld] Re: Prop pitch, GPH, cruising speed, RPM Sorry, it is a single 360. Also, since it sounds like there is a ton of chrysler marine experience here........... (I am a chrysler guru, but this is the first marine engine I have ever messed with) This 360 has heavy cast iron rockers, is that a marine thing? (Ticks like a mech cam too, I haven't opened up a cover to see if it does have one, or has lifter/adjustment issues) It also has a single plane intake, I think it came off of the 318, (Which has different port size in the auto world). The manifold looks like the 2bbl single plane on the 215hp 318's, and just like the 273 manifold. It is on the 360 now. Is 7-8kts a good speed? I am happy with it, I just was wondering if it was supposed to be a slow boat, or it was because it is under power. Last boat was a 1976 Bayliner 22', with one of those little inline volvo AQ170hp engines, it ran like stink, 14-16kts, and it took more power to run at 7kts. But it was too small, took rough water like crap, and was a Bayliner. I go out in the Prince William Sound, so choppy water is normal, and it is nothing for 6'-8'ers to come up in the middle of the trip. What is "Cupping"? I am new to boats this small, also, another inch on the pitch I too think would make a difference. The main issue I have with running it 3300, is the 4bbls are kicked in, and it seems to be burning about 12gph. I am getting about 1/2 gallon per mile at 7kts. As far as the cummins, my truck has a 350-375HP tweaked VE pump cummins, I just wonder how the bellhousing/transmission thing will work. I guess find a twin disc from a yacht re-power? Being a trailer boat, I cant run a huge prop. Picture: http://s12.photobucket.com/albums/a227/dodgetkboy78/?action=view¤t=l_28b39ea8f8be461bb97a15af905e6228.jpg<http://s12.photobucket.com/albums/a227/dodgetkboy78/?action=view¤t=l_28b39ea8f8be461bb97a15af905e6228.jpg> --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/unifliteworld?hl=en -~----------~----~----~----~------~----~------~--~---
