Scarab 33 AVS- Doing Transom the transom, Should I raise the X dim? (bravos w/ 4blade
#5
I removed the transom assemblies before measuring where things were. ( I figured i would use the old holes when I replaced the transom.) After reading about things I am interested in raising things. I will try to measure things tonight.
As far as I am have found out:
1. the more blades the higher you can run drives.
2. More blade is harder on drives
3. The faster you go the more benefit raising the drives.
4. X-dim should be around 17.5" for nice all around performance, which results in 4.5" centerline of the prop shaft (correct?)
5. Y-Dim distance between crankshaft centerlines on a twin engine boat. It is 34" on BBC without tall decks.
6. If you run extension boxes you can lift the drives more.
As far as I am have found out:
1. the more blades the higher you can run drives.
2. More blade is harder on drives
3. The faster you go the more benefit raising the drives.
4. X-dim should be around 17.5" for nice all around performance, which results in 4.5" centerline of the prop shaft (correct?)
5. Y-Dim distance between crankshaft centerlines on a twin engine boat. It is 34" on BBC without tall decks.
6. If you run extension boxes you can lift the drives more.
#6
Gold Member
Gold Member
The X goes up and the engines go up raises the center of gravity.(if you use stock drives) Wouldnt it be better to do boxes and or shorties or both?
Also, do you have enough room under the hatch?
Also, do you have enough room under the hatch?
#7
I would raise it 2 inches. If you are running three blade props now You have to go to four blade props. You can always shim it back down easily. It is hard to raise the drive. Most performance boats need to go up at least 2 inches. I went up 2 inches with my 34 Scarab and it helped handling drastically.
I just installed a box on my Daytona and went up another inch. If you want to talk about a high X dim. - last year it was at 1 inch, now it is at 2 inches ABOVE the lowest point of the hull.
I just installed a box on my Daytona and went up another inch. If you want to talk about a high X dim. - last year it was at 1 inch, now it is at 2 inches ABOVE the lowest point of the hull.
#8
Registered
iTrader: (1)
Several good points in here. I agree with the idea that if you are doing the transom, raise the X, as you could always space back down. That being said, with a Bravo application, once the prop starts surface piercing, IMO, drive longevity starts to get a lot more questionable.
#9
Ok here are some images. The transom has been replaced but not cut.
Notice how little room there is above the exhaust holes. I am not sure how to go higher without buying new exhaust?
So if it is 7" from the transom assembly (gimble housing) to the bottom hull (directly under the output shaft), if I add 9.25" to that I get a 16.25" X-DIMENSION.
If I subtract that from 21.825", I get a propshaft depth of 5.575".
Should this be changed?
Thanks
Notice how little room there is above the exhaust holes. I am not sure how to go higher without buying new exhaust?
So if it is 7" from the transom assembly (gimble housing) to the bottom hull (directly under the output shaft), if I add 9.25" to that I get a 16.25" X-DIMENSION.
If I subtract that from 21.825", I get a propshaft depth of 5.575".
Should this be changed?
Thanks
Last edited by cyrus77; 10-13-2015 at 01:01 PM.