X-Dimension 101

[HP 600SC]

This is the best I could do.
Scot please move this to the "how to area". I could not get in there. Dont forget my tee-shirt
size large :D
http://www.donzi.net/photos/xdim1.jpg.jpg

http://www.donzi.net/photos/xdim2.jpg.jpg

http://www.donzi.net/photos/xdim3.jpg.jpg

http://www.donzi.net/photos/xdim4.jpg.jpg

http://www.donzi.net/photos/xdim5.jpg.jpg

http://www.donzi.net/photos/xdim6.jpg.jpg

http://www.donzi.net/photos/xdim7.jpg.jpg

[oldLenny]

What is dimension "A" for the Alpha or is that drive one of the V-SSM designations?

[HP 600SC]

Lenny, the stock X dimension on current production classics is 14 1/2 for alpha or bravo.

[RickR]

In the mid 90s Merc sent out a Tech Bulletin suggesting the keel measurement should be taken from the "True Bottom" instead of the "Actual Bottom".
See http://www.donzi.net/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=002436#000010
http://www.donzi.net/photos/rryan25xdimension.jpg

[HP 600SC]

I remember that. These photo's are from a Mercury
book from 2000. This is the current methood.
Rick maybe we can share the shirt!! LOL :D

[harbormaster]

Ted,

Can you retype these or at least scan these pages with a scanner? These would look alot nicer.

[HP 600SC]

Sorry they look so bad...I dont have a scanner. :rolleyes:

[BERTRAM BOY]

Here's the dimension sheet right from Donzi.

BERTRAM BOY :D :D :D

http://WWW.DONZI.NET/PHOTOS/WINDXDIM.JPG

[oldLenny]

ahhh,...now it is starting to all make sense wink In this above pic I "assume" the sharp keel is just a graphical reference when in fact it is of the radius variety...right?...and we use the 90 degree rule here. Raising the "X" here might be say moving it uo to 16" for a 1 1/2" gain...correct? Scott P as quoted a while back said 2 1/2" is max on the Alpha and Bravo. Is this amount adviseable on the 16? (an ooold one)
Will I get away with 2"? I understand all about risers and deck/rail exhaust clearances and such, I am thinking about prop blow-out here. If two inches puts it into the hull/deck seam then it is obvious to me.

[HP 600SC]

Lenny, you got it!! up 2" on your 16 will be a good thing. 16's have too much bow lift so if you lose some it will only help! and it will be good for another 5.5 MPH.

[Rootsy]

HP,

so if i am reading this correctly then the 16 AND the 18 both have the same X dim @ 14 1/2?

actually i think there is room for at least 1 1/2 up on my 16... exhaust clearance anywho... what is the threshold of prop blowout in terms of raising X dim on say an alpha?

hmmmmmm i'm beginning to scratch just from the thought of another spring project... :D

[HP 600SC]

Jamie, the X is the same on all 3 Classic's 16 18 & the 22 @ 14.5 inches. I have raised the propshaft height(without raising the X dimension)
using a special bravo outdrive from mercury, on an 18 and on a 22 classic....3 inches higher with fantastic results, typically 5-7 MPH top end.
Also the Bravo and Alpha are the same length so you use the same X dimension on either one.
I beleive that there is enough room in the engine compartment to go up 2 1/2 inches on the 18 and 22
and still close the engine hatch.
You can not purchase the special Bravo drive from Mercury.....they are just loaners to boat manufactures, but you can buy an Imco shortie
and raise the propshaft height 1 or 2 inches without having to change your X-dimension.
Way easier and probally cheaper in the long run
and the best part is you dont raise your engine
height and screw up you center of balance. the threshold is 3 1/2 inches before you will blow out.
Hope this helps,
Ted M.

[Rootsy]

to replace the alpha with the bravo transom assy requires two extra bolt holes correct? same cutout in the transom?

i kinda have a small issue raising the motor even 1 inch though... without adding the scoop :rolleyes: so it'd be so long to stealth mode... :(

actually ive wondered what running a bravo on the 16 would be like vs the Gen II hanging off the back at the moment... least with the bravo there are upgrade options...