Folding prop won't work, need feathering

[realem]

I have a kiwi Prop on my 29ft mono hull Kelt. Have had the prop for about 5-7 years and very happy with performance in both forward and reverse. I purchased extra blades which have come in handy. Maintenance is pretty low just grease whenever I haul the boat for bottom paint. Boat seems to go even when there is growth on the blades. The engine was a 2gm originally and they worked fine. I upgraded the engine to a 2gm20f and prop works just fine on that engine as well.. The boat had a Gori folding prop low thrust in revers and on one instance would not open due to growth.

[Cadence]

Originally Posted by Jerry Woodward

How much is too much? It measures about 2" between the strut and the prop hub. We discussed cutting the shaft, and it might then barely fit, but I am reluctant to do this only to find that it is still touching.

Jerry, I agree. The shaft that could be gained doesn't look like enough. Is there a chance of also modifying the sked slightly along with reducing the shaft.

[spaman]

I have had a Kiwi prop for the last 7 years on my B393 and am very happy with the performance, which I reckon adds at least 0.5-0.75 knots to sailing speed depending on conditions and perhaps only loses maybe 0.25-0.5 knots to steaming speed. The very reason for having one is for the wind powered performance. Manouevrability is also very effective once you have learnt to optimize the prop walk.
On the negative side, it is vital to service the prop (which is easy) once per year when hauled out as this cannot be done in the water. Also I am still searching for the best antifoul, bearing in mind the blades are composite and therefore an etching primer/antifoul (ie Velox) cannot be used. I have tried basic ablative antifoul, Doctor Barnacle, PropShield amongst others with limited success. In the Med the growth during the summer in warm waters is very fast, so extended periods of sitting still will promote significant growth. As always, the best method is regular passage through the water (great!!), but otherwise manual cleaning/scraping is necessary every couple of months to clear the barnacles and maintain good performance. This is not so good if using the grease or wax option as every clean takes the product off as well.
I recently had to replace my prop shaft due to electrical corrosion/insufficient anodic protection (a whole other story), but had to replace with a shortened shaft to have room for the extra shaft anode and to be able to pull the prop without having to drop the rudder (I have a brand new standard shaft to sell when I get round to it). I was concerned with potential vibration issues, but fortunately my fears were unfounded.
In a nutshell I will stick to the Kiwi prop which is not ridiculously expensive, easy to fit, has good after sales service and does what it says on the package.

[singlespeed]

Kiwi props are great. Easy to adjust pitch and replace broken or damaged blades, even underwater. Fishing line cuts can be repaired with epoxy. Disadvantage over FoF is that the Kiwi prop feathers, so lines, nets and bags will still hang up on it when sailing.

[roland stockham]

Notspeaking from direct personal experience as I have never owned a boat with either a folding or fethering prop but I think the are are big advatages to fethering over folding. All a folding prop does is reduce drag whereas a fethering prop allows you to match the prop to the conditions. Means that when plugging into into heavy sea that increases the load you can reduce the pitch allowing the engine to run faster. Normall this happens to an extent as prop slip increases with load but I think fethering props do it more efficiently, thats why they fit them to ships.

[Adelie]

Originally Posted by Jerry Woodward

My current clearance is 2", so only 1" longer than the "1 shaft diameter rule". This doesn't seem to me like a big deal. But even if I cut the shaft to a 1" clearance, that wouldn't help. I would have to shorten it to less than a half inch between strut and prop hub, and I don't want to do that.. No, I'm not going to relocate the strut.

I wasn’t thinking of relocating at much as getting one the was not swept or was swept the other way.

[jacktheflyer]

I went from fixed props to the Autostream feathering prop on my Fusion 40. They are a great product but are not as good as the fixed props of course. Note that the blades on a feathering prop are fairly straight and have little washout. If doing it again I would have liked to try the Flexofold.

[CarinaPDX]

Whichever prop you choose you should cut the shaft back - that long extension amplifies any balance problems, including when barnacles/line/net/etc get caught on the prop.

If speed under sail is your highest priority then make the adaptations needed for a folding prop. Folding props sometimes have issues with opening and backing down. Self-feathering props have a little more drag under sail but still far better than a fixed blade, and are great for backing down and reliability. Unfortunately the great majority of feathering props have flat or only slightly curved blades in order to minimize drag under sail at the expense of efficiency under power. The only self-feathering prop that I know that has a proper curve to the blades, and hence improved efficiency under power at the expense of a small amount of drag under sail, is the Luke (which is very simple and heavy - a century-old design). There may be others now but the best-known self-feathering are less efficient than the Luke or a fixed prop under power.

Controllable-pitch props, like the one with my old Sabb engine, are pretty impressive for getting the most out of the engine as well as feathering under sail for low drag but they are rarely seen and not cheap. With 2 blades rotated to vertical orientation in the aperture there is almost no drag under sail. The auto-adjusting props apparently work well when properly matched to the boat, but a very poor performer when not matched, and getting the right one can be a trial.

The point I would make is that there is a trade-off between performance under sail and performance under power. Serious racers will usually go for the folding props. But cruisers should reconsider for their own situation. Most cruisers put in a fair amount of time motoring so having an efficient prop for powering is also valuable. There are comparisons of the various props on the internet which you should seek out, and look at the efficiencies (i.e. fuel consumption relative to forward power).

Greg

[jonarck]

Love the KikiProps on our Leopard 44 cat (also, previously in our 1997 Catalina 34 Mk II. And at $1500 each, including shipping, were a great deal.

Jon Arck
Second Star
North Palm Beach, FL

[Jerry Woodward]

Originally Posted by George DuBose

I love my Flex-O-Fold. I had a similar problem, the blades when folded would have hit the skeg. I considered cutting out a bit of the skeg, but I cut the prop shaft on the inboard end, shaved 1/2" off the "P" strut, took slightly shorter blades from FOF and I am very happy with the results. FOF props got very high ratings in a prop test by Yachting Monthly, I have much less prop walk in reverse and they are supposed to have good "braking" power. As I dock slowly, I don't use the engine to brake often.

Now this just might work for me. I need about 2" off the length of the shaft for the props to clear. If I cut the strut tube just at the base of the vertical support, I will gain about a half inch. So, I could cut 2" off the inboard shaft and 1/2 inch from the strut. The prop hub would then be 1/2 inch from the strut bearing. I would obviously install a 31/2" cutlass bearing in place of the current 4". My contact at FOF thinks 1/2 inch clearance is fine. Is this too close?

[geoleo]

Originally Posted by Jerry Woodward

I'm really bummed that my new Flex-O-Fold props will not work. Terrapin has a skeg rudder and the props overlap the skeg when folded. I did measure and consulted with FOF but we still got it wrong. The good news is that FOF will refund my purchase price and pay for return shipping. I can't speak highly enough about the FOF customer service.


I believe this means that any folding prop will have this same issue, so I am now looking at feathering props. I've read the YM review of props and many threads here. Wow, they are expensive! To help me decide, I'd like to hear from feathering prop owners who have them on smallish cats with a similar power train. Terrapin is 32' and has two inboard Yanmar 2gm20F with shaft drive. I know Beliezesailor has Kiwi props and seems to like them. Anyone else?

I had KIWIS that jammed- They took them back and refunded.--frankly they are not very strong. Also have plastic blades. Best IMHO is MAXPROP>

[slug]

Originally Posted by Jerry Woodward

Now this just might work for me. I need about 2" off the length of the shaft for the props to clear. If I cut the strut tube just at the base of the vertical support, I will gain about a half inch. So, I could cut 2" off the inboard shaft and 1/2 inch from the strut. The prop hub would then be 1/2 inch from the strut bearing. I would obviously install a 31/2" cutlass bearing in place of the current 4". My contact at FOF thinks 1/2 inch clearance is fine. Is this too close?

Propellor shaft thrust movement and cutless bearing lubrication..free flow of water ..are considerations

Also remember that sooner or later you will need to remove the prop.

You must leave room for the prop puller or devise another way to pull it off

I don’t know the minimum length of a cutless bearing

[Paul Howard]

I had Maxprops on my previous catamaran and liked them, but they do need occasional re-machining to get the slack or dings out, also very expensive.
I have Kiwiprops on present catamaran with 2gm yanmars. Kiwiprops less expensive, have interchangeable carbon fibre blades and are easy to grease without disassembling them.
IMHO the maxprops had slightly more push forward, with the kiwiprops slightly better in reverse, but both good gear.

[sailingchiro]

+1 for Maxprops. I purchased mine for $600 a piece used then had refurbished for $500 each. In it for $2200 for both. There are several used for sale.

[fstbttms]

Originally Posted by Mr O

I have the classic from years ago, which is nearly impossible to install/remove in the water.

It can be done quite easily by a knowledgeable diver. I have personally removed, installed and repitched many dozens of Max Prop Classics underwater.