MB Sports 21' boat with GT-40 310HP - can I put a steeper pitch for more speed?

[splasher2k]

I am looking at a really nice 1997 MB Sports Boss 210 tournament boat (mid engine direct drive) with a 310HP GT-40 (351) motor. The owner says speed tops out around 44MPH and that there is tremendous pulling power. It is a bowrider model and we were hoping to use it as a multipurpose boat. Most of the people we would be towing are pretty light and not expert skiers or boarders, so extreme low end pull isn't a major issue for us.

Could we reprop this boat to get 50+ MPH out of it or is the hull design of a tournament boat a limiting factor? 310HP on a regular 21' 2500lb bowrider should easily get 50+? We would do a lot of cruising as well, so wouldn't a steeper prop improve fuel economy too?

If I am way off base here, please let me know. I have no experience with inboard direct drive tournament boats.

Thanks for any input!

 

[jestor68]

Re: MB Sports 21' boat with GT-40 310HP - can I put a steeper pitch for more speed?

I suppose you can, provided the motor can still turn within it's WOT rpm range.

The inboard tournament ski boat is not designed for cruising. If extreme pulling power is not a major requirement, perhaps you'd be better off with a 20-21 foot stern drive powered boat. They are more efficient than the inboards for various water related activities.

Most inboard ski boats I've seen do about 45 mph(or less). The main reason for the lack of speed is the fact that you cannot trim the boat. The prop thrust is downward, like you'd have a stern drive trimmed all the way down. There is no way to trim up to raise the bow. The faster you go, the more the bow is pushed down, limiting top end speed. Changing the prop will not change that angle of thrust.

 

[steelespike]

Re: MB Sports 21' boat with GT-40 310HP - can I put a steeper pitch for more speed?

Actually the straight drive tends to lift the bow but the ski boat is designed to lay down so it provides a stable platform
for pulling skiers. If your looking for speed that boat isn't for you.If you check prop prices I think you may be a bit shocked.

 

[Bondo]

Re: MB Sports 21' boat with GT-40 310HP - can I put a steeper pitch for more speed?

I am looking at a really nice 1997 MB Sports Boss 210 tournament boat (mid engine direct drive) with a 310HP GT-40 (351) motor. The owner says speed tops out around 44MPH and that there is tremendous pulling power. It is a bowrider model and we were hoping to use it as a multipurpose boat. Most of the people we would be towing are pretty light and not expert skiers or boarders, so extreme low end pull isn't a major issue for us.

Could we reprop this boat to get 50+ MPH out of it or is the hull design of a tournament boat a limiting factor? 310HP on a regular 21' 2500lb bowrider should easily get 50+? We would do a lot of cruising as well, so wouldn't a steeper prop improve fuel economy too?

If I am way off base here, please let me know. I have no experience with inboard direct drive tournament boats.

Thanks for any input!

Ayuh,.... Welcome Aboard,.... Yes, the hull is the limitin' factor...

Ya bought a Farm Tractor, not a Hot-Rod, Speed Demon...

 

[splasher2k]

Re: MB Sports 21' boat with GT-40 310HP - can I put a steeper pitch for more speed?

Thanks for all the info - this was a pre-purchase question, so you saved me making a mistake! I will go with a stern drive runabout instead.

Enjoy the rest of the weekend.

 

[jestor68]

Re: MB Sports 21' boat with GT-40 310HP - can I put a steeper pitch for more speed?

Thanks for all the info - this was a pre-purchase question, so you saved me making a mistake! I will go with a stern drive runabout instead.

Enjoy the rest of the weekend.

Good decision.