bekasi
New member
Are there any downsides to the vee types than the straight transmissions? Life expectancy etc? Our design has been specified with vee drives which is almost a norm with catamarans
Vee drive transmissions
- Thread starter bekasi
- Start date
oldsaltoz
New member
Never had a cat with 'V' drives, this configuration is often used to save space but has the downside of adding more weight in the stern.
Preferred configuration is a sail drive a bit further forward than on a mono hull or better a shaft drive to the engine/ gearbox mounted at the bottom of the hull access steps, this has the advantage of a lift off box and full all round access.
On my current Cat I have a collision bulkhead aft, then a deep storage locker with a bulkhead forward with the engine room and another bulkhead forward. This configuration means there is not even a hint of diesel anywhere on the cat.
Good luck.
bekasi
New member
A stupid question from the novice-its been some very tense moments with this design re all systems.The cockpit is 20ft(L) x 16ft(W) but because of the height of the engines & displacement nature of the hulls ,vee drives were chosen.Are there any special arrangements re the location of the shaft seal area that i should be careful about? Will PSS dripless seals be ok if headaches are to be avoided re servicing with vee drives in place ?
Latestarter1
New member
V drives not common in Europe, however in US where outdrives not at all popular V drives are in many applications. Assume we are talking direct mount V drives here.
Can dig out some pictures of some installations I have been involved with. Biggest watch out is that motor is nose down and unless you ensure you have suitable vent lines engine will be prone to air locking on filling with coolant. Deere have comprehensive installation instructions which need observing to the letter. I always require vent line between turbo housing and header tank even if is not in application guidelines, turbo housing is prime location for big gob of air to become entrapped, with serious overheating consequences.
Lining up can be a pain, used to mock up a dummy engine out of alloy box section to make job less tedious.
If you pm me I will look back at what I have.
Can dig out some pictures of some installations I have been involved with. Biggest watch out is that motor is nose down and unless you ensure you have suitable vent lines engine will be prone to air locking on filling with coolant. Deere have comprehensive installation instructions which need observing to the letter. I always require vent line between turbo housing and header tank even if is not in application guidelines, turbo housing is prime location for big gob of air to become entrapped, with serious overheating consequences.
Lining up can be a pain, used to mock up a dummy engine out of alloy box section to make job less tedious.
If you pm me I will look back at what I have.
D
Deleted User YDKXO
Guest
V drives are not common in motor boats but they are used on some models by the likes of Ferretti and Sunseeker and others. Obviously, the main advantage is that the engines are pushed further aft releasing space for accomodation but the disadvantages may include stern down trim issues and lack of access to the sterngland. The trim issue can be addressed by the builder by moving other heavy components forward like the fuel tanks and generator.
I had V drives on my last boat (Ferretti 46) and to be fair the V drive gearboxes never gave a problem in the 5 yrs I owned the boat. Certainly the boat performed better with the trim tabs down but I'm not sure whether thats a trim issue or a hull design issue because I've driven other Ferrettis with standard shaftdrive and they needed tabs too. I did have the feeling that adding the extra V drive gearbox in the system may have reduced fuel efficiency but I'm no expert so I cant say for sure and by how much. IMHO you shouldnt be concerned about V drives providing the builder has addressed any trim issues and the sternglands are accessible
I had V drives on my last boat (Ferretti 46) and to be fair the V drive gearboxes never gave a problem in the 5 yrs I owned the boat. Certainly the boat performed better with the trim tabs down but I'm not sure whether thats a trim issue or a hull design issue because I've driven other Ferrettis with standard shaftdrive and they needed tabs too. I did have the feeling that adding the extra V drive gearbox in the system may have reduced fuel efficiency but I'm no expert so I cant say for sure and by how much. IMHO you shouldnt be concerned about V drives providing the builder has addressed any trim issues and the sternglands are accessible
bekasi
New member
Thanks Deleted User,my research on the web shows alot of exaggerated comments labelled against the vee drives due to the lack of accesibility to the stuffing box etc...I guess if the designer/builder puts it correct,nothing should go wrong.
What about the reduction in efficiency secondary to mechanical losses?
What about the reduction in efficiency secondary to mechanical losses?
D
Deleted User YDKXO
Guest
As I said I can't answer that but basically you're putting 2 gearboxes in the drivetrain where there is normally one so there must be an additional efficiency loss although I guess it must be quite small
Andrew_Fanner
New member
I have v drives in Jedi.
As others have said there will be additional mechanical losses but with a well designed and specified system they will be fairly small. More checks to remember, the v boxes need oil level checks as well as the normal boxes and may also have pressure switches/gauges to check as well, again, I do. Idiot lights for pressure in the v boxes and gauges in the normal ones. Different spare oil, and naturally you can't get the one you need on a Sunday afternoon. ATF in the normal boxes and EP90 in the v. Additonal oil coolers may be there too, which will be more work for the relevant water pumps.
And the engines/gear boxes sit over the stern glands rendering access all sorts of trouble, I will have to take an intercooler off to get at one of them. Winter project I think.
Otherwise they have been fine, touching wood!
As others have said there will be additional mechanical losses but with a well designed and specified system they will be fairly small. More checks to remember, the v boxes need oil level checks as well as the normal boxes and may also have pressure switches/gauges to check as well, again, I do. Idiot lights for pressure in the v boxes and gauges in the normal ones. Different spare oil, and naturally you can't get the one you need on a Sunday afternoon. ATF in the normal boxes and EP90 in the v. Additonal oil coolers may be there too, which will be more work for the relevant water pumps.
And the engines/gear boxes sit over the stern glands rendering access all sorts of trouble, I will have to take an intercooler off to get at one of them. Winter project I think.
Otherwise they have been fine, touching wood!
bekasi
New member
Will it be ok if there is good side access and to have either PSS dripless shaft seal system or either of these?
http://www.chatfieldmarine.com/shop...ue+Water+Shaft+Seal+%96+Commercial+Model.html
OR
http://www.kiwiseal.com/
http://www.chatfieldmarine.com/shop...ue+Water+Shaft+Seal+%96+Commercial+Model.html
OR
http://www.kiwiseal.com/