Prop two or three blade?

S

samwise

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Our Westerly Storm is fitted with an 18hp Volvo 2002 and a two blade prop. So far we have found this set up adequate. However, we are planning to set off for the Med this season and I deduce from our own experience of the area, various conversations and YBW postings that Med cruising can place a lot of emphasis on motoring. OK you say, so buy a motor boat! We will of course try to sail as much as possible, but my understanding is that an efficient power option is useful and could be a lifesaver is some circumstances. Now we come to the options. A three blade should provide more drive than a two-blade, but there is obviously an increased drag factor. Folding props might be a solution and the Bruntons are lovely, but cost an arm and two legs, plus I have reservations about the engineering complexity and vulnerability to damage.
So, I've narrowed it down to either, stick with what we've got or go to a fixed three blade and live with the drag. All views welcomed.
 
Please read previous posts on this. I have mentioned many times about options but look at Volvo 3 folding prop for 2002/3 series grea bit of kit a. Whatever you do dont by a fixed 3 bladed prop for a Storm.

Kind regards.

Peter.
 
If you intend to do a lot of motoring then I would fit a 3 bladed prop. There's a lot said about drag so much so that members would have you believing that your towing 1/2 hundred sack of spuds astern, where as in reality your talking of 1/2 knot at the worst. BUT once you get into a head sea or a marina, you just see the difference - in a head sea you can drive better and in a marina the boat responds better to the throttle.
I would presume that you're heading for the med to do some gentle cruising in warm conditions - so why the fuss about 1/2 knt, when you have better handling?
 
go for a three blade prop. it will give you more effic motoring, in heavy seas you will have full thrust and equally important it will give you greater control when reversing into a berth. Everything in sailing has benefits and drawbacks, I went for a Gori folding prop, great bit of kit transformed berthing improved motor sailing no end but gave me a hiccup this year at slow speeds when the blades went out of balance due to one of the flexible stops disintegrating. At the time I could have thrown it away but on reflection go for three blades. fixed or folding.
 
If you're staying with the Volvo 2002 and your current prop. is correctly sized then I don't see what you would gain by changing the prop.. You will have the same maximum of 18 bhp [minus the 5% transmission losses] available for propulsion in either case.
 
I gained at least 1/2 a knot when I replaced my fixed twin blade for the Volvo folding 3 blade. The power is also better now when under engine. I know 1/2 knot doesn't seem much but it makes the long hauls much quicker.
 
Went from a 3 blade to a 2 blade last winter. First season with 2 blade saw me motor and sail a long way(Whitby to Tower Bridge and back). She sails noticeably better with the 2 blade and motors very well. Perhaps I use a bit more diesel when motoring but I do not have to motor quite as often - and its much better sailing then motorsailing. If you are primarily a motorsailor go for 3 blades if you are primarily a sailer go for 2.
Martin
Martin
 
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