Top Speed?

[SeaDooSam]

Hi all,
I was wondering if someone could tell me what top speed I should be expecting for my boat. It is a '96 Chaparral 1830 sst. It weight just shy of 2500 lbs. It has a 4.3lx (190hp) and turns a 19 pitch prop. Anyone have an estimate. Could it hit 50 with one or two people?

Thanks!

 

[Bondo]

Could it hit 50 with one or two people?

Ayuh,.... If it does, it'll be the upper limit,....

 

[H20Rat]

50 on gps would be generous but not impossible.. mid to high 40's. I have a '94 deckboat with the 4 barrel 4.3 (200 hp or so, but this motor is very healthy) with a 21p prop, and I'll hit lower 50's, but that is also with a hull that has almost no deadrise.

 

[roffey]

I have a 20 foot bow rider, with just me (210 lb) full tank of gas I can hit 54.2 on the gps. My boat is a 198 lx Stingray, prop is a 23 inch (factory), 4800 RPM, my motor is a 4.3 TKS (2 BBL). My goal is 55, LOL.

To answer the OP your prop is wrong for top end but great for pulling (water sports)

 

[Texasmark]

www.go-fast.com, Bam prop slip calculator. Fill in what you know and leave what you don't blank. Punch the calculate button. If you are running a heavy boat or a deep V then expect your prop slip to be "fair-to-middlin", like 20%. If not it will be less. A good, light, fast stock rig could expect 10-12%. GPS speed preferred for accuracy. Tachs should be pretty close. Gear ratio needs to be known and exact.

 

[SeaDooSam]

Thanks! I just left the prop that came with the boat on it. I am hoping she will hit 50 with 2 people . :joyous: However, I do know that stingray hulls are built for speed. Chap hulls are built for comfort and a tiny bit of speed. So, it definitely won't be as fast as a stingray.

 

[roffey]

Thanks! I just left the prop that came with the boat on it. I am hoping she will hit 50 with 2 people . :joyous: However, I do know that stingray hulls are built for speed. Chap hulls are built for comfort and a tiny bit of speed. So, it definitely won't be as fast as a stingray.

with the right prop IMHO you should hit 50 with two people, you just might have to change the prop. Its not a bad idea to have two props. I have a 19 inch for skiing and a 23 for booting about the lake.

 

[thumpar]

The Chap is probably a tad heavier than a stingray and maybe a lower deadrise. With the right setup you might touch 50mph.

 

[SeaDooSam]

Is a 23inch prop ok for a 4.3 ? Would it get on plane still. Also wouldn't it make the Rpms not in the right range?

 

[spoilsofwar]

Is a 23inch prop ok for a 4.3 ? Would it get on plane still. Also wouldn't it make the Rpms not in the right range?

It's hard to say as a general rule. My 4.3 Volvo came with a 23p three blade, same as roffey's boat, from the factory. If you try one, and your wot RPMs are in the recommended range, well there ya go. You will definitely be moving the boat's performance curve toward the high end though.

 

[SeaDooSam]

Ok thanks. Maybe I'll test it out once I see how she performs with the 19.

 

[frantically relaxing]

...The difference between say 46mph and 50mph is 3 minutes on a 10 mile ride. And the difference between 50mph and a reasonable 30mph cruise speed in 10 miles is 8 minutes.

The BIG difference: Driving 30mph for 10 miles will take about 3 gallons of gas, 50mph will suck up around 10 gallons..

...is it worth an extra $20 just to get there 8 minutes sooner? (and don't forget, you have to come back!)

My point is, since driving WOT is rare (and expensive as hell), why is top speed so important? Just curious--

That all said, my 4-banger '07 Babyliner 175 would hit 48 on the GPS at 5100rpm with the as-installed 19" prop w/2:1 Alpha One at 4400' altitude...

And- My 8.1Gi powered Chap 260ssi would go exactly the same speed.

So if you're near sea level, and it's running okay, your V6 powered 18'er with a 19 prop should get REAL CLOSE to 50-- But I'm going to guess 48...

 

[SeaDooSam]

Ok thanks. I just wanted to know what it should run at to make sure it is not tired. I don't go at full throttle much anyway and when I do it is not because I want to get there faster. It is because it is more fun!

 

[drrpm]

That's a 20 year old boat with a carbureted V6 and it probably topped out around 45 mph new. Low 40's would still be reasonable performance. It takes a lot more power to go a little faster.

 

[SeaDooSam]

I'll let you guys know. Hopefully we can get it to work this weekend.

 

[Scott Danforth]

Download free GPS app to pgone, go for run, look at GPS speed and answer your question