Legs in the air

[jfm]

Re: Down

Yes there are various bellows, sorry if I confused but I was referring to the mission critical bellows, which if they fail let the sea in. The ones you refer to aren't mission critical in that sense, AFAIK, or are they?

JFM

 

[ari]

Re: Down

All the Volvo 290 legs (current) have the hydraulic power trim/tilt. I think these have been about since the mid '80s.

You are quite right about the previous generation Volvos, they had an electric motor which wound the leg up and down, as you say, a bit Heath Robinson! Those legs didn't trim at att however, they were fixed.

One other thought on this wholeMerc/Volvo debacle, Volvo 290 legs are usually duoprop (apart from the 4 cylinder petrols which were always single propped). Most Mercruisers seem to be single prop, although I beleive they are now doing the Bravo 3 leg with twin counter rotating props like the Volvo Duoprop.

Having had boats with single and duoprop legs, I certainly favour the duoprops for close quarter handling and smoothness and performance, not to mention total absence of cavitation. A bit like having a four wheel drive car rather than two wheel drive. The benefits are not immediately obvious, but once you've had one you learn to appreciate the subtle difference.

Any thoughts?

Ari.

 

[jfm]

Re: Down

Yes, I think the one major contribution Volvo made in recent years is the duoprop. Jolly clever. The others, Merc included, copied (and I presume pay royalties, though I dunno who has the patent??). Yamaha are now even putting duoprops on big outboards.

It's interesting to look back over the years. In the 1970s and perhap 80s Merc made by far the best engineered products IMHO, in both outdraves and outboards. Volvo were basic, heath robinson tilt mechanics etc. Yamaha were nice at the engine end but not in the bit that got dipped in the water. Suzuki similar, their gears seemed to be made of something very soft. But now it's different, Yamaha make fantastic outboards (on balance I still prefer and buy mercs but Yam are certainly better in a number of respects) and Volvo make the duoprop with proper hydraulic trim.

I think these days it depends on the particular HP that you want, in some cases Merc is better and in other cases not I guess

JFM

 

[ArthurWood]

Re: Down

jfm - I have the Alpha One manual in front of me; you are right, to some extent; there are three bellows: for UJ, exhaust, and gearshift cable. They seem to be independent of each other. I had water entering my 19ft boat and the yard said it was due to a rupture in the gear shift bellows. Presumably if the exhaust bellows ruptures, water could enter the engine and if the UJ bellows ruptures (I've had that too) water enters the boat. The exhaust and shift bellows are easily visible on my boat, but I've not seen the UJ one. Must be tucked away or I haven't looked hard enough. Anyway I learned something useful from all this Thanks.

 

[Col]

Re: Down

The trailer position on mercuiser/volvo/omc legs brings the leg right up causing quite an acute angle in the drive shaft,this has 2 back to back universal joints,(like on car prop shafts ) without these the leg would not turn to allow steering.This shaft runs in a gimball bearing to stop it whipping about uncontrolably.this whole assembly is housed in the bellows to keep water out.It is connected to the leg one end,and the transom shield the other.If the engine is run(irrespective of gear position) at this high angle,the u/j's rub on the inside of the bellows and will, in time, wear through.the only thing keeping the water out would then be the dust seal on the gimbal bearing (i.e- it won't)hope this clears any missunderstandings.