Need prop help. 1999 Yamaha F50 on Maxum 1700 XR (16 foot actual)

[gotboostedvr6]

The New to me boat is a 1998 Maxum 1700XR bow rider with a 88" (7'4") beam. Empty hull weight is around 1250. It is slow to plane and doesn't carry the bow very well. I'm looking for advice on what type and pitch of prop I should be looking into testing.

I removed the powertech 4 blade Scb4 stainless prop to measure the actual pitch. The stamping was Lazer etched and is missing. Condition of the prop is like new and has never been worked.

The measured prop diameter is 10.286" and has mild cupping.

At 8" it measures 11.185 pitch
At 7" it measures 12.655 pitch

The best speed on this boat I've seen is 27 mph, this same prop and motor on a lighter hull has seen 33mph. The cavatation plate is even with the bottom. It will show some cavatation when it gets sloppy or I try to turn at speed.

There is no hook or dome on the bottom.

This motor can fit 12.3" props max so with my current 10.28" prop it should be well buried.

I have 6",10",and 12" jackplates at my disposal. The steering cable would have to be replaced to use any of them.

I know I'm underpowered but for now this will have to suffice.

The tach on the boat is the original mercury/maxum and it has a dial on the back for? I plan on trying to hook it up soon and get rpms to report.

 

[Watermann]

Really need to know what RPMs you;re getting at WOT and speed by GPS. I'm thinking a 50 matched with small light boat a 3 blade pitch would be 13 for a 50 and 12 in a four blade. With the size of the boat the little 50 is expecting to move one would need to know the WOT RPM and speed you're getting now.

The dial on the back is for how many cylinders your motor has

 

[gotboostedvr6]

On the old hull running even with the bottom I saw 5800 rpm at 33mph.

It will be a week before I can give you current rpm

 

[steelespike]

Couldn't find a 1700 BR but the 1700s listed were 1500 to 1700 lbs for an outboard.rated for 120 or 115.
I'm thinking an 11" may be a good starting point.
But get your present rpm before any new props. Of course you may be able to have your present prop tweaked a little
based on your performance.The prop shop can get you your accurate pitch as well.

 

[gotboostedvr6]

The hull is a Maxum 1700XR. Sorry for the misinformation.

 

[steelespike]

The hull is a Maxum 1700XR. Sorry for the misinformation.

Thats 1575 dry weight.

 

[gotboostedvr6]

Changed to a 3 Blade Aluminum 10.875 x 11
Black Diamond p/n QA2070X
27 mph 5800 rpm with slightly faster planning, better bow rise.

I measured the pitch to be 10.8 to 11.0.

It looks to me that I have a thrust issue that only a larger diameter prop and less pitch will cure.

Eyeing up a 12.2" solas in 10p.. what do you all think?

 

[gotboostedvr6]

20 % slip tells me I have a setup issue that has room for improvement.

 

[steelespike]

Have we verified the tach is accurate?I think at 27 mph the hull presents more drag higher slip. I think the
boats rated for something like 125 hp so your way down on push.
Going further down in pitch your slowing the boat even more.I guess you figure the larger diameter will temper the rpm.
At 5800 and 12% slip the speed is about 26. with a 10"prop.
What is the rpm on the original prop?If rpm is reasonable use the original prop and add some smart tabs.
Carefully applied to just enough lift to improve hole shot.

 

[gotboostedvr6]

Thats 1575 dry weight.

Does dry weight include the standard motor?

 

[gotboostedvr6]

I know my question depends on how the manufacturer interprets at what point of assembly the hull is weighed. Sometimes the weight listed is only the fiberglass parts.

Ive been told that dry weight is derived from the production weight of the boat as it is shipped from the point of manufacture with standard equipment.

It is also my understanding that all Bayliner/Maxum boats of this era had Force outboards on them i was told they were rigged at the factory.

 

[steelespike]

My guess would be that the primary package was a Force motor but likely could be up graded.
I think a package boat was dry weight with the motor weight was extra.
I do wonder if dry weight means not in the water thus "dry". I suppose dry could mean no fluids or motor added.
Fluids could be pretty serious weight, live wells and large gas tanks. and/or couple of batteries.

 

[gotboostedvr6]

I ended up trying 4 props but none provided more then 27mph. I was able to cruise at 18 19 mph and got incredible mpg but going that slow got old real fast.

This is the new setup.
Should go like hell now.

 

[Watermann]

I would say just about tripling the HP should bump your top end up.