Rage owners, need some help. Have a 25 Rage midcabin with a 26" B1 and I'm seeing about 16-18% slip at all RPMs. Engine is a 496HO and it turns 5000RPMs with a B1 X drive. Before starting in on the prop, I wanted to check the drive height against other 25's. Measurements I'm interested in are 1) from the bottom of the transom (not the running pad), what is the height to the center of the up/down swivel pin (or the middle of the trim sensors), 2) what is the height to the top of the drive (ie: top of the drive housing), and 3) if you are able, what is the drop from the back of the transom to the center of the prop shaft at neutral trim. Thanks for any help!

Rick, we have your same boat in a 2007 model. Call Neil at the shop(270-343-6911), he can get the measurements for you.

Are you booked for the Jamboree?

Nordic Gary

Rick,

On my 2002 Rage, with a 496HO and a B1x the dimension from the bottom edge of the transom to the center of the gimbal (center of trim sensor) is 14 1/2". That eyballing from the center to a spot on the fibre glass and measuring down to the edge.

Hope that helps.

Pat

Rick,
Measuring your actual X-dimension is fairly easy.
Measure the vertical distance (not along the transom) from the driveshaft centerline (also where the trim sender and limiter switch covers are) to the bottom of your pad. This will probably be in the 18" to 19.25" area.
Just run a 4' level, framing square, or yardstck parallel to your pad (you can temporarily duct or masking tape it in place) and drop another yard stick or measuring tape vertically down from the center of the switch covers.
Knowing this # will help you prop the boat (most knowledgable prop shops will ask), and if need be, adjust your propeller depth with spacers (lower) or shortys (raise).
I think your slip#s can be addressed with more propeller cup, or a 5 blade. BTW, 16/18% is a little high (have mine down to 13% from 20%) but not that bad. A spacer (available in various sizes 1/2"/1"/etc) may help too.
Regards,
Steve
PS if you are running a Bravo 1 propeller, deduct 1.5"s from it's rated pitch (ie 26 = 24.5), when running the #s. They are less ptich than advertised. You may find using this correction factor that your slip isn't as bad as it appears.

Thks for the data guys. My transom measurement is 13 1/2 and my prop shaft center line is 5 1/2 inches below the running bad. Talked to a few shops today and understand both these measurements are "low" for this hull, so I'm zeroing in on the drive is mounted a little low and I'm guessing the prop itself needs some work. Will need to decide on next steps.

Steve,

I thought the consensus was that the correction to the designated/published Bravo prop pitch to get the effective pitch was subtract 1.0 inch. Is the 1.5 inch a relatively new determination or was I previouisly missinformed?

Rage,
Some prop shops use 1.0", some use 1.5". Keep in mind there are "production variations" between the blades themselves (which is why pitch matching Bravo blades is an effective part of blueprinting), AND the amount of cup added (or removed) to a propeller does change the pitch.
Heavy cup adds at least .5"s, removing cup decreases pitch at least .5"s. That's why most Merc Lab Bravos come with very little cup, unless you need it, and/or ask for it. It's an easy place to pick up RPM. However, on high X-dimesion boats like ours, it doesn't work. Removing cup just results in bad slip %s.
Steve

Steve,
Good info on the impact to pitch from cupping.

Rage,
I asked this question on the prop forum to get a professional opinion. Julie says - 1" on a stocker for slip/speed calculations on a B1 up to a 32". She says more than 1" on the 34s" and 36s".
Then, take your modifications (if any) into consideration.
Regards,
Steve

Steve,

Thanks for the follow up.