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  • #6114
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    I am planning to replace the standard 2 blade fixed prop on our B37 by either a feathering or folding prop. However the more that I look on the internet the more conflicting reports I find leaving me increasingly confused.

    At the moment top of my list is the 3 blade Volvo Penta folding prop, but I have also been considering Flexofold, Brunton, Kiwi, Maxprop, Gori

    This may seem to be stating the obvious but I am looking for

    Power in reverse as least as good as the old 2 blade fixed prop
    Reliability of the mechanism
    Smooth power in forward
    Less drag when sailing

    Most of the manufacturers claim all of the above, but then they would when they’re try to persuade you to part with 1000 pounds!

    What recomendations or horror stories do you have to share?

    #7426
    Webmaster
    Participant

    I have the Volvo 3 blade folding prop on Playtime and it ticks all the boxes. It has been on the boat for 5 years now. It only gets cleaned/greased once every 12 months but continues to fold without problem. Reverse is fine (but I do have have the 50hp engine) and hull speed is achieved ahead.

    I had a Brunton on a previous boat and that was very good, especially motor-sailing. It is debateable whether it is worth the extra money, though.

    #7428
    Webmaster
    Participant

    I have a 2-blade Bruntons on my B32 ‘Another Fantasy’. Yes. it was expensive but performs very well. Lots of thrust gives good boat speed under power at lower RPM than with the original prop, it works well in reverse and, when you stop the engine and start sailing you can see the boat speed increase when the prop feathers.

    Ian Culley

    #7431
    Webmaster
    Participant

    I also have the 3 bladed Volvo prop. It is very easy to maintain and has not given any problems mechanically. My only area of concern is that the 3 segment annode needs replacing fairly regularly. It was every six months until I fitted a Galvanic Isolator and now it is approx 8-9 months. It may be different in other areas or marinas.

    Regards, John Linsdell

    #7433
    Webmaster
    Participant

    Dear all,

    I have a two blade volvo folding prop on my 36 with a 2020 engine. This works very well and I would reccomend this prop. it was not that pricy either fitted from new. It does introduce different materials though and the three piece anode is 50% wasted at least, each year but the large anode against the leg is almost as new. Fred Edgar Tortola Dawn was interested in this point.

    Keith and Carole Wavedancer

    #7434
    Webmaster
    Participant

    All,

    We have used three different props on our B32/Volvo2020 combination. The original fitment was the standard Volvo two bladed folder, which from the functionality point of view was fine. It folded when sailing, it drove the boat forward up to hull speed, and reverse stopping power was acceptable. On the downside, the rapid wear of the three anodes was alarming, at times less than five months with only the steel pins left. This despite having fitted a galvanic isolator. After two seasons I could see signs of de-zincing, probably caused by the lack of anodes when they had worn out.
    I then tried the two bladed Bruntons Autoprop. This does was it says on the box. Speed was good, the anode appeared to be lasting longer, and reverse stopping power was better too. It feathered OK, but the engine needed to be in gear to stop the prop rotating when feathered. Motorsailing was where the prop came into it’s own, as it really does produce power at a much lower engine revs, however, I have my doubts about the effect on the engine.( see below)
    The cons were, when reversing out of a berth and selecting forward, a large amount of revs were needed to engage forward drive. The first time we did this, for several seconds I thought the prop had fallen off! For the season we used the Autoprop I never got used to this, and never seemed to give it quite enough revs. Funnily enough, going from ahead to astern was almost instant. The second con was that on two occasions in a certain seaway the prop appeared to “gear down” and drive was all but lost. The first time was coming out of the Rompot Sluice in Holland, wind against tide, very short chop, with the B32, which is a light boat, “nodding” in the chop. We were in a line of boats all doing 6 knots, when we hit the chop, I suddenly realised the boat astern was nearly on our swim platform, and the speed had dropped off to 1.5 knots. A very large amount of revs pulled some back, but not all. The second time it happened was going up the Thames near Canvey Island, with similar conditions, when exactly the same thing happened again.
    During the next winter I had to replace the exhaust manifold elbow at the rear of the engine, where the raw water feeds back in, as a small pin hole had developed, leaking water. On taking it off I discovered that there was an alarming amount of carbon in this elbow, and I put this down to the engine running under a laboured condition whenthe prop gears up. This is probably confirmed by the fact that during that season, the hull had black stains around the exhaust area.

    The next prop is the three bladed Kiwi (composite blades), and it is a superb piece of equipment. It produces hull speed at around 2800 revs, similar to the original Volvo. Stopping power is brilliant. I have to warn crew members to hang on when I give it a short burst in reverse, as they tend to fall over! A couple of times I have nearly left my wife on a pontoon when reversing out of tricky marina berth, and giving it too many revs (only slightly above tickover!) It has no anodes as the hub is stainless, and now the anode on the saildrive leg even lasts a year at least. It feathers immediately the engine goes into neutral, with minimal drag, but the biggest bonus is the reduction in engine vibration and noise. Without all the weight of metal blades flying round, it is remarkable. It can be antifouled with ordinary hull antifoul to keep barnacles at bay, and if the power delivered it not quite to your liking, then it can be simply adjusted up or down a turn or two to alter blade pitch. WE haven’t had black exhaust stains on the hull with the Kiwi prop either, which does rather confirm my diagnosis.

    If anyone is interested I have a lightly used one season old Autoprop for sale, but I suppose I have just talked my way out of a sale!!

    Robin
    Moonbeam

    #7436
    Webmaster
    Participant

    Thanks to Robin, Moonbeam for your interesting message regarding folding props. Could I ask a couple of questions regarding the first prop, the Volvo folding type. What damage is caused when the annodes have worn away. Is the de-zincing confined to the prop or does it effect other areas. Does the annode on the saildrive protect everything else except the prop. I have no complaints regading the performance of my three bladed Volvo prop but the annode wear is a bit worrying. I also may have one for sale soon.

    Regards, John.
    Loblolly

    #7437
    Webmaster
    Participant

    Regarding the short life of the anodes on the 3 bladed Volvo folding prop, try putting a ring of paint around each anode at the fixing hole. The main reason that the anode disappears so quickly is because it corrodes around the fixing bolt and flies off.The ring of paint reduces this problem – I can now manage a complete season on the same anodes.

    Regarding de-zincing, there is some evidence of it on my prop, but on the 3 blades only, not on the boss or saildrive. I guess if it gets bad, the blades alone can be replaced.

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