Are newer boats faster?

[cobra 3.0]

I have a 1986 Peterborough 16' open deck boat with a 3.0(140 hp.) Cobra drive. Top speed on it is about 38mph GPS when I am alone in the boat. Are new boats any faster with the same size motor and length of boat? i.e. Are the new 3.0's any faster? Do they rev higher?<br /><br />I am asking because I hear things like: In the 1980's boats were going 30-40 mph, in the 1990's they were going 40-50 mph, and in the 2000's they are going over 60 mph. I'm guessing this has more to do with larger boats and motors being sold? Or is there something I'm missing here?

 

[POINTER94]

Re: Are newer boats faster?

There are several reasons. Todays boats are lighter than those of a decade ago, new materials and manufacturing techniques.<br /><br />New hull designs are somewhat, more efficient than previous years. (Multi-stepped hull) <br /><br />Greater hp per liter than 10 years ago and more efficient means of transfering that HP to the water.<br /><br />Put it all together and you get slight increases in speed. I think your generalization was a bit ambitious.

 

[mrn714]

Re: Are newer boats faster?

The displacement of the motors remains about the same, but the fficiency and designs of both the boats and engines have increased the speed by lower drag and other factors. I would not say that a 2004 would do better than a 1980 by much more than 25%, but believe it would be based on efficiency and design rather than the displacement shown on the hood.

 

[WillyBWright]

Re: Are newer boats faster?

The 3Ls haven't changed very much. Different ignition system is about all. They were never intended for performance as much as cheap reliability. If you want performance, get a small block. They make tons of stuff to perk those up. 3Ls are made more for commercial air compressors and tractors. If MerCruiser wasn't buying so many of them, they'd probably have been discontinued long ago.<br /><br />I hear they're considering making 3L EFIs. Even so, I wouldn't expect much of a performance gain if any. Just easier to operate. People don't seem to understand the concept of choking anymore, or pumping the throttle a couple of times before starting. That's so 20th century.

 

[Bhamil]

Re: Are newer boats faster?

You guy's are all correct. I have a 3.0L that is alright at low to medium RPM's where it runs solid, but, top end leaves a lot to be desired. In speed, I'm talking about. What do you guy's think, could gear ratio and prop selection be something that slows us down? Also, is it something worth looking into changing?

 

[rodbolt]

Re: Are newer boats faster?

hello<br /> 3.0's with TBI fuel injection have been about for at least 6 years maybe some longer. the 3.0 FI motor is a sweet heart. the only drawback is the throttle response when returning to ide. it hesitates for 3-5 seconds at 1100 rpm before dropping back to 800. a bit unnerving when manuvering in the marina. other than that they still make about 140 hp as they have for many years. its a workhorse but they need to eliminate carbs altogether and go with EFI.<br /> the carbed 3.0's can be a beast sometimes. wont idle smooth and bog problems. good luck and keep posting

 

[bluewater19]

Re: Are newer boats faster?

I recently saw a stingray ad. I says 18 ft runabout top speed 48 mph with a 3.0 liter. Cost $11,000 with trailer. I don't know how they are built but would like to check out the 20 ft center console they make.

 

[cobra 3.0]

Re: Are newer boats faster?

I just went to the Stingray site and it shows their 18 ft 3.0 boat going mid to high forty mph! That's 10 mph more than mine! That's quite a bit of an engineering improvement! <<br /><br />Are the gear ratios the same on the drives?

 

[Bhamil]

Re: Are newer boats faster?

Hey, Rodbolt, you're in my neck of the woods. I'm in Va. Beach. What do you know about modifying a 3.0L to FI? I have a carb and you're right; it's got a slow response time, and bogs down.

 

[cobra 3.0]

Re: Are newer boats faster?

I heard that putting on electronic ignition(if you don't have it already) improves starting and general performance. Here's the site.<br /><br /> http://www.pertronix.com/

 

[rodbolt]

Re: Are newer boats faster?

hello<br /> ben <br /> call jerry's marine in charleston SC.<br /> talk with Doug I belive and see if Marine power is offering it as a kit yet.<br /> carbs suck. I will be glad when the last are gone.<br /> which wont be to long.<br /> good luck and keep posting

 

[Walt T]

Re: Are newer boats faster?

Cobra what is your current wot rpm? Its possible gear ratios are the same. 38 mph out of your boat is pretty good and makes me think it's running good. If you want to spend a boatload of money to go a little faster, well then go right ahead. Otherwise enjoy your boat. It's not all about speed.

 

[Cannon]

Re: Are newer boats faster?

Al good points made above. Another one is that the newer 3.0 engines are 135 hp at the prop. The 140 was 140 at the crankshaft. The 140 was probably closer to 120 at the prop.

 

[cobra 3.0]

Re: Are newer boats faster?

DieselWalt, I know my boat is running well and I enjoy it as is too! Just curious as to why newer boats are faster. I suppose spending money on a Petronix and an injector system kit would get me more umph...whether its worth the bucks? ... probably not unless something was wrong in the first place.

 

[Bhamil]

Re: Are newer boats faster?

Cannon; Is that because of different gear ratios, different props, , better engine performance, all the above? What's your thoughts on it? Oh, and Dieselwalt is right, that's pretty good speed...if I could get that kind speed out of my '88 Bayliner Trophy I would be very happy!

 

[Bondo]

Re: Are newer boats faster?

I am asking because I hear things like: In the 1980's boats were going 30-40 mph, in the 1990's they were going 40-50 mph, and in the 2000's they are going over 60 mph. I'm guessing this has more to do with larger boats and motors being sold? Or is there something I'm missing here?

It seems that you're taking a Very General Statement,<br />And Trying to apply it to a Very Specific Engine/Drive......<br /><br />

Are new boats any faster with the same size motor and length of boat? i.e. Are the new 3.0's any faster? Do they rev higher?

No... <br /><br />For all you poor souls out there still beating yourselfs up, Trying to Squeeze a little More out of those little 4 bangers, Check This Out....<br /> http://cgi.ebay.com/ebaymotors/ws/e...0442&item=2454376451&sspagename=STRK:MEBWA:IT

 

[cobra 3.0]

Re: Are newer boats faster?

Cool stuff Bondo! Does it mean I will have to change my prop pitch and/or gear ratio?

 

[Spidybot]

Re: Are newer boats faster?

Cobra,<br /><br />Your performance (hole shot and top speed) is a compromise that is decided by the power you have and the force needed to move your vessel.<br /><br />When your boat and engine are tuned as best possible and your "drivetrain" runs with a minimum of waste and slip, you get a performance pretty close to any theoretical calculation.<br /><br />To decide if your rig is anywhere near the ideal you need to know what rpm you reach at wot, running the boat with your normal load.<br />If you are within the recommended rpm range, you're close to correct setup. You can tweak it by removing weight (cheapest performance boost you'll ever get), trimming the drive and chosing the right prop.<br /><br />As a prop works like a fixed gear, you'll have to balance hole shot against top speed within reasonable limits and the mentioned wot range. One inch pitch down equals 200 rpm up and all experience says to reach for the upper range limit.

 

[Cannon]

Re: Are newer boats faster?

Bem, I cannot say about gear ratios and other things. There are just so many variables with a boat. A smooth bottom is just that a smooth bottom.<br /><br />It is true that props have become better. If I really had to put a reason for it I would say that the biggest factor may be weight. Boats tend to gain weight as they get older too. We loose track of all the junk we have dragged aboard over the years.

 

[cobra 3.0]

Re: Are newer boats faster?

UU, yeah my WOT is within specs. I'm one big happy boater...all is well with my setup. I'm asking about the turbo and if it's installed it means generally more umph. Do I need to change props or gear ratio to compensate for the extra power? Or does it only mean quicker take off and higher loads at similar speeds.