"Brian J Goggin" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > On Fri, 7 Nov 2008 20:33:15 +0000, Julian Tether > <[EMAIL PROTECTED]> wrote: > >>Parglena has 120hp and a 23x16IIRC 80% aspect blade, made by Crowthers >>of Oldham there is only 1" between the counter and the tip and the same >>between the skeg and the tip. It all works fine. > > Excellent. Thank you. > > It has been suggested that with a small prop there is no point in my > getting a larger (say 130hp) engine. But would the extra hp be useful > for braking, turning etc? > >> From what you say there is plenty of clearance above the blade as for >>below if you are worried about clearance you could fit a drop skeg >>(provided the waterways are deep enough) which would involve very little >>modification. > > Loads of room above the prop. Most of the waterways we're likely to go > on have enough water for our 4' draft but low summer levels could be a > problem. The other drawback to a drop skeg would be when dry-docking, > although we might be OK if we lined it up properly (there's really > only one dry dock we can use). The other thought I had was to replace > the current box-section skeg with a thinner bar, supplemented by > another bar well above the prop to help hold the rudder in position. > > Incidentally there are pics of the prop etc amongst other things on > http://www.pbase.com/bjg/big_iron
OK firstly Parglena will stop in her own length from canal speed with ease, that is on of the reasons that I stayed with 6cyl rather then 4 when I re-engined. Also starts well ........:-) What would I do in your case? Move the shaft up, fit a cavitation plate over the prop and go for at least a 30" prop, It looks like the shaft was dropped many years ago and I can see why it was done, to make it easier to run the barge with no cargo because a higher/bigger prop may well have led to cavitation problems hence my thoughts on fitting a cavitation plate. I would also prefer to see the Prop closer to the stern post as even though there is a tube round the shaft it will still put a lot of strain on the shaft and bearings if you increase the size of the prop. One thing that will happen is that with a bigger prop and more thrust you steering will become very heavy as there is no counterbalance on the rudder. Ill try and remember to email you a photo of the underwater part of Parglena when I get home Julian
