For those wondering about the results of the ‘prop swap’, my apologies for the delay in posting them. This was due to work commitments… but here goes! First I’ll say that due to various circumstances, we didn’t do as much testing done as we would have liked but here’s what we did get!
In view of the weather forecast for last Saturday and no other confirmed participants, Ageing Youth and I decided on a change of venue. So we took 3 props on a jaunt to Boulogne for a bit of swapping… with moule and frites thrown in!
Having survived the ‘Slipway from Hell’ and a leisurely One and a half hour crossing from Dover we got down to the task of unscrewing nuts on Boulogne Beach.
I originally had 4 props to try. A 19” Titan, a 19” Vengeance, a 19” Laser II and a 21” Laser II. The 19” Titan I discounted before I left due to its weight. Having had the chance to compare the Vengeance and the Titan side by side, the Titan really is a lot heavier. My original ali weighs in at around 2 kilos. The Vengeance is 4 kilos but the Titan is nearly half as much again at almost 6 kilos. I just felt that this was a bit big & heavy for my Alpha One leg and didn’t want to risk it causing any long-term stress. The Titan stayed at home, despite the fact that I suspect it would probably have worked the best.
The first prop I tried was the 19” Vengeance. According to theory, since my 23” ali was giving WOT revs of 3,800, the Vengeance should have exceeded the recommended maximum revs of 4,400. In fact, it only gave 4,200 revs. (All the revs quoted were with 4 on board and almost full fuel tanks…. And fully trimmed in)
The acceleration was certainly greater than the ali, as was reversing… which caused flooding over the engine box. Thank goodness for deck bilge pumps! Maximum speed was about a knot faster than the ali. However, it did seem a little odd in feel and seemed to slip at certain points.
I then planned to try the 21” Laser II but it had the wrong fitting for my boat, (though with after thought I may have had an adapter). Anyway, that left the 19” Laser. This fouled on my sacrificial anode fin. So that came off! I have to say that I found the Laser II so horrible that we didn’t even get it up to full speed. It had poor acceleration and again felt as if it were slipping. The bow of the boat did seem to be too high too! OK, the removal of the sacrificial anode may have caused problems, the prop was a little the worse for wear with many chunks out of it… and the moule was beckoning by now…. but for whatever reason, it didn’t seem happy on my RIB. I know people love them and on your boat they may be great… but it didn’t seem to suit my set up
So, we returned to the beach and replaced my 23” ali…. Well it may not have as much acceleration but it was like putting an old pair of shoes back on! So for that reason and what I would term a ‘rattle’ that appeared with all of the steel props, I have decided to stick with ali. Steel Developments have now supplied a 21” aluminium Black Max and re-funded the difference. I will let you know how that goes next time I’m out.
Many many thanks to Searider for the loan of his Vengeance…. (You should have it back by now Duncan).
Also to Rogue Wave for the two Lasers. Thanks Stuart.
And to Richard B for the Titan, which I would have dearly liked to try but I would never have used due to its weight. That’s still here Richard, call me and we can sort out how to get it back to you.
Finally thanks to Ageing youth and his partner Katherine for holding my nuts…. And washers!
The moule and frites by the way were delicious!
Mike C
