speed of boat and hull design

[Zer0]

I have a 1972 180SRV. It has a brand new 115 optimax 2 stroke and I achieve 50 M.P.H on the G.P.S. W/a 21 pitch alum. prop. I was told the boat has a max speed in a way, True? Question 2 - The motor is just broke in and before I change the prop because I'm short about 200-250 R.p.m at W.O.T, will It loosen up and give me a little more "should I wait"? or should I tweak the prop? Prob. going to go with the smart tabs because of the chine walking. The higher speed might give me the r's also. win win situation? what do you think.......

 

[steelespike]

Re: speed of boat and hull design

Before you mess with the prop be sure your setup is fine tuned especially the height.If you feel the setup is good then a prop may be the next step.
One of the experts should be along with suggestions.Going to stainless should help speed but may require a further drop in pitch stainless should also allow more height and thus more rpm and speed as I said the experts should be able to help.

 

[haywaraa]

Re: speed of boat and hull design

50mph with 115hp? i'd be happy with that. are you sure your tach is accurate? you may have all ready achieved the correct rpm. If you do make changes, don't expect any major improvements as your doing fine all ready.

 

[Zer0]

Re: speed of boat and hull design

Yes, I have that system check tach or smart tach/gauge for my r.p.m's and the speed was 50m.p.h with a g.p.s @ 5500-5575. told I need to reach w.o.t @5800.....

 

[Dhadley]

Re: speed of boat and hull design

Depending on how much time is on the motor the r's may come up. The computer won't let you get everything until there's some time on it. It should get full rpm after 10 hours (that's 10 hours above a certain rpm) but may take longer.

Yes, most boats do have a hull speed. IE - it'll reach a given speed fairly easy. After that it takes changing the set up, blueprinting the hull and / or more power, way more. Stability may become an issue.

 

[BF]

Re: speed of boat and hull design

while you may be able to get more out of your setup, I agree with the above posts that it's doing pretty good already. Chinewalking becomes an issue with my boat when it gets much over 50 as well. Tabs would probably help, raising the motor a hole might too (?). I've never worried too much about squeezing the last few mph out of the top end. I'm content to have a boat that jumps out of the hole and runs like a scalded ape to it's top speed. My boat is mainly used for water sports which is usually done much slower than 50 mph .

BTW, mine's a 16' ski boat hull (identical to glastron CVX, but a different name badge), with V150 merc. Swings a 19p aluminum, gets to 6K rpm...

I'm guessing, but thinking you might get snappier performance across the board with a 19p on yours. (possibly sacrificing a few mph on top).

 

[Zer0]

Re: speed of boat and hull design

Mr. Hadley, I have 11 hrs. on the motor. I did my break in to perfectley. Can anyone tell me if the motor will loosen up and give me a few more "R's"? Maybe after 20-30 hrs?? I've been told no. Seems to me like it should loosen up a little, but there I go thinking again. Thanks guys.

 

[Dhadley]

Re: speed of boat and hull design

If you've achieved the correct amount of time above the required rpm, that's about all you'll get.

 

[Zer0]

Re: speed of boat and hull design

WOW! Fast return. Confirmed everything for me. This forum is top shelf. Thanks again. That's service.