lesson on twin stepp take off
VIP Member
03-28-2009, 11:51 AM
#33
Registered User
Join Date: Feb 2002
Location: Toms River NJ
Posts: 1,422
Likes: 0
Received 0 Likes
on
0 Posts
On a step bottom boat on the rear pad there would be two 1/2 or 3/4 brass thru hull openings that runs through your engine compartment out the transom or sides, They will have shut valves so if they leak you can shut them down. What happens on take off excess air gets trapped in the padded area and causes excessive prop slip and blow out. The Blow offs get the air thats trapped out from under the boat and reduce the slip from start.
you will see on the back of a lot of number 6 Drives these 2" black tubes coming off the back of the drive and they come up over the drive, this does the same it release the excess air from a step bottom boat and reduces prop slip. Helps the boat get on plane faster.
Thats why I asked what kind of boat and does she have a pad on the rear of the boat.
you will see on the back of a lot of number 6 Drives these 2" black tubes coming off the back of the drive and they come up over the drive, this does the same it release the excess air from a step bottom boat and reduces prop slip. Helps the boat get on plane faster.
Thats why I asked what kind of boat and does she have a pad on the rear of the boat.
03-28-2009, 12:50 PM
#35
On a step bottom boat on the rear pad there would be two 1/2 or 3/4 brass thru hull openings that runs through your engine compartment out the transom or sides, They will have shut valves so if they leak you can shut them down. What happens on take off excess air gets trapped in the padded area and causes excessive prop slip and blow out. The Blow offs get the air thats trapped out from under the boat and reduce the slip from start.
you will see on the back of a lot of number 6 Drives these 2" black tubes coming off the back of the drive and they come up over the drive, this does the same it release the excess air from a step bottom boat and reduces prop slip. Helps the boat get on plane faster.
Thats why I asked what kind of boat and does she have a pad on the rear of the boat.
you will see on the back of a lot of number 6 Drives these 2" black tubes coming off the back of the drive and they come up over the drive, this does the same it release the excess air from a step bottom boat and reduces prop slip. Helps the boat get on plane faster.
Thats why I asked what kind of boat and does she have a pad on the rear of the boat.
the boat is a 2003 powerquest revenge with a small pad
03-28-2009, 01:03 PM
#36
Charter Mod
Charter Member
this may be just another stubd queston and may not mean much hear with theas boats but has any dealer R&R the drives lately ? at the rear trim ram pin with the black caps covering the nut's there is a white plastic spacer in between the nut hard wear that could be installed wrong and it will change the drive trim angel a bit not leting the drive tuck in as far.they do this becouse there is a differents between bravo 1 & 3.and some guys will change that around by not knowing where to put it.on bravo 1 the spacers need to be installed with the grove part pointing a way from the bow of the boat or a way from the boat in general. well i'm shur it's fine but if not it a easy thing to look at any ways.it dose sound like the x is high but that is where the top speeds come in.you would think the manufacturer,s would by now say to you oweners to install lower unit drive spacers by now to help stop the blow out. merc dose sell them spacers also.just an idea is all this is.good luck and have fun this year boating.
I've had that exact thing happen after having a drive worked on with the Gun. It definitely can be overlooked, and made my boat cavitate like hell until it was swtched back.
03-28-2009, 05:46 PM
#37
this may be just another stubd queston and may not mean much hear with theas boats but has any dealer R&R the drives lately ? at the rear trim ram pin with the black caps covering the nut's there is a white plastic spacer in between the nut hard wear that could be installed wrong and it will change the drive trim angel a bit not leting the drive tuck in as far.they do this becouse there is a differents between bravo 1 & 3.and some guys will change that around by not knowing where to put it.on bravo 1 the spacers need to be installed with the grove part pointing a way from the bow of the boat or a way from the boat in general. well i'm shur it's fine but if not it a easy thing to look at any ways.it dose sound like the x is high but that is where the top speeds come in.you would think the manufacturer,s would by now say to you oweners to install lower unit drive spacers by now to help stop the blow out. merc dose sell them spacers also.just an idea is all this is.good luck and have fun this year boating.
Thanks for all the replys!
03-29-2009, 03:12 PM
#38
A friend had a 34' PQ that also has the 2 large steps. His drives had spacers on it when he bought it. Possibly for this very reason?
__________________
Some people are like Slinkies - Not really good for anything, but they
bring a smile to your face when pushed down the stairs.
Some people are like Slinkies - Not really good for anything, but they
bring a smile to your face when pushed down the stairs.
03-29-2009, 04:36 PM
#39
Registered
Join Date: Jun 2003
Location: Pittsburgh
Posts: 6,130
Likes: 0
Received 0 Likes
on
0 Posts
So the two long vertical tubes I saw on the drives on the 42 Fountain at Cleveland were the blow off vents? They sat directly above the props and just looked like to tubes that went vertical and would stick out the water. The sales guy said they were to venitlate the props. But he made it sound like they provided air to the props so that the motors could get them rev'd up.
03-29-2009, 05:47 PM
#40
Gold Member
Gold Member
[QUOTE=4mulafastech;2831045]The reason is if the drives are tucked 'too' far at speed in a hard turn, it is more likely to spin-out/roll a twin stepped hull due to the added stern lift. I never have my drives tucked all the way in when turning (rule #1 of driving a stepped hull). QUOTE]
The drives should not be trimmed below level when turning at speed...period.
The drives should not be trimmed below level when turning at speed...period.
