Need a little more speed

[Home Cookin']

Re: Need a little more speed

is it worth it, to pay a couple thousand dollars so you can go a few miles per hour faster (while burning more gas)?

Your boat is not a speed boat. Compare your boat to a pick-up truck and a donzi to a corvette.

 

[UncleWillie]

Re: Need a little more speed

You really think an 18 foot CC boat with a 300 HP outboard is only going to top out at 45 MPH?

NO! That is why I said....

... the numbers do not look correct.
I have an 18 ft bow-rider with a 220hp I/O
It just barely makes 60mph on a good day, under ideal conditions, lightly loaded.
Working Backwards...

220 hp = 60mph (Given)
88 hp = 44.2 mph.

Something else may be wrong! :blue:
It appears you should be able to make 40mph without issue...
Power may not be the problem.

I think he should be making 40+ with what he has now; Not ~30!
And well Over 60 with 300hp!

He may have a Weight, Rigging, or Trim issue,

 

[ezmobee]

Re: Need a little more speed

So a 140 looper would be a johnny/rude and be about the same weight I have now

Yep.

 

[haulnazz15]

Re: Need a little more speed

I dunno, I don't remember going over 40mph in an 18' tri-hull with a 90HP Johnson V4 on the back. I would imagine they'd be close to the same weights, his being a few hundred pounds more. We were definitely running quicker than 30 though, probably upper 30's.

 

[MH Hawker]

Re: Need a little more speed

Its is simple really ,,,speed costs how deep are your pockets

 

[etracer68]

Re: Need a little more speed

I run about 37mph with a 1987 90hp, on a glass 16ft loaded, with two people. Thats propped with a 17p. I think your doing good with that motor. First thing I would do is, loose the whale tale. But I dont see to much improvement. Even with the 140hp looper, maybe another 5 to 8mph. just my .002.

 

[Campylobacter]

Re: Need a little more speed

A few years back I was messing with props, and found fairly big differences between the three I tried. The composite was the worst, aluminum OK but SS the best (same order as price of course ). The composite and SS were the both 3 blades and the same size, and I got a better hole shot and about 3 mph better on the top end with the SS.

 

[Home Cookin']

Re: Need a little more speed

for some, if you switch from alum to ss, you have to drop (or is it add?) a pitch size for equivalent performance, due to the weight of the prop. and don't forget to try different diameters.

then you have to question whether the performance difference is worth $300.

and loose the whale tail.

 

[ondarvr]

Re: Need a little more speed

It's interesting that people suggest as a first option to remove the fin, it is one of the few tools you have to work with right now that will cost no money and possibly gain you a couple MPH.

 

[Mischief Managed]

Re: Need a little more speed

NO! That is why I said....



I think he should be making 40+ with what he has now; Not ~30!
And well Over 60 with 300hp!

He may have a Weight, Rigging, or Trim issue,

I think low 30s is going to be pretty normal for an 18 foot Sailfish CC with only 88 HP. Those are pretty ruggedly built and have a big fuel tank for an 18 footer. I seriously doubt it's a light boat, especially with a T-Top added. A smaller and shorter CC with a smaller fuel tank, like a Trophy 1703 with a 90 HP OB, won't top out much more than 36 MPH, according to boattest.

I believe drag is a function of the square of speed, not the cube. See: Drag equation - Wikipedia, the free encyclopedia. My own experience and testing proves it to be reasonably accurate on boats

 

[Home Cookin']

Re: Need a little more speed

on his direct question--removing the canvas on the t-top to reduce drag and increase speed: theoretically, yes. Practically, it won't be noticed but the lack of shade will. You can also always travel down-wind and down-current. Removing your windshield, and requiring all passengers to lie flat on the floor, will also help, if it's all that important to add a mph.