DRAGONFLY Trimarans User Forum

Has anyone fitted a Varifold prop to a DF1000?

I'm very interested in reducing the vibration which seems to be coming from my Gori 2 blade.
The boat has a 15x12 and doesn't seem to have quite enough bite.
The gears are fine and there's no excessive play. If folds and unfolds as it should.

Comments about Flexofold vs. Gori are also appreciated.
I would also like to hear any comments about various pitch and diameter experiences.

The Varifold website talks a fair amount about reducing vibration, and the blade shape seems to me to be a better design.


Steve B.

I do have this same problem, so I am also interested of any news.

I have a Varifold (made by Bruntons in the UK) 2-blade and it is superior to the Gori in my opinion. You will need a 16x12 right-hand. You should send them your shaft nut to match thread because the ones Quorning used on my boat (hull #13) are considered a non-standard thread by Bruntons. Also my keyway is 7mm whereas Bruntons and most other makers use a 6mm keyway. I had a prop shop open-up the Bruntons keyway to 7mm and I also had them sell me a "stepped key" as an emergency spare, which is 6mm on one side and 7mm on the other, just in case I ever need to fit another prop and don't have machine-shop access.

I also have tried the Volvo 3-blade folding prop and liked it even better, though the drag is probbaly a bit higher. The Flex-o-Fold is what Quorning is now using, and should also be considered.

If you have vibration it could also be a "shaft-whip" induced by mis-aligned components in the coupling or a bent drive shaft.

I have a vibration and brought the entire shaft, coupling and prop to a prop shop. They found the prop shaft was bent and we replaced it. I still had a vibration and found I was able to reduce it by engine alignment. I reduced it further by installing a drive-saver flexible shaft coupling (a polymer disk that goes between the transmission and shaft coupling faces). I'm planning to re-do the engine alignment to better tolerances, and I think that will improve it further.

It would be worthwhile doing a careful alignment before winter storage (while the boat is still in the water) to see how much of the vibration you can eliminate. Convention is that the shaft must be in alignment to within .002" but I would strongly suggest you use .001" as your standard. This is because the DF-1000 shaft is only 1" and is long for that diameter without any supports. The dripless shaft seal offers no support restraint and that is also a factor, I suspect.

Here is a link to a shaft alignment procedure you will find very helpful. http://www.svdaydreamer.com/downloads.htm Scroll down to the section on engine alignment, and take special notice of the footnote about the typo error in the article. The typographical error is about halfway down the left column on Page 4. The phrase "(e.g. 1 to 2 and 2 to 4)" should read "(e.g. 1 to 3 and 2 to 4)". (Tool Hint: The author suggests using vice-grips but there is no room to turn the DF1000 coupling with that, so I use a small C-clamp.

Do this yourself. Unless you have a back problem I do not recommend you have your mechanic do the elignment. Most are not patient enough to give you the .001" (or better) tolerance you need. It would also be expensive.

Yesterday I installed a new Varifold 15 x 13 RH two blade prop.
The difference in motoring was remarkable to say the least.
I can still just achieve max rpm with the engine, but I can also get 5.5 knots motoring speed at only 2000 rpm.
There's still a little vibration between 2200 and 2700 rpm, but not as bad as before, although now there's no real need to run in that range.

The Varifold needs a quick shot of forward to unfold it.
Just putting it in reverse will not unfold the blades most of the time.
It's something I'll get used to.
Overall, I'm a happy camper.
Rick Steadman of Varifold was very helpful.

Steve B.

Steve B. wrote:Yesterday I installed a new Varifold 15 x 13 RH two blade prop.
The difference in motoring was remarkable to say the least.
I can still just achieve max rpm with the engine, but I can also get 5.5 knots motoring speed at only 2000 rpm.

Steve B.

I have got the original Flexifold on my DF1000 and my max speed when motoring in calm water is just below 6.5 knots. I think it is not too much.
What's your cruising and max speeds with your new propeller?

Is it good at choppy seas? Mine is really poor, it is not worth to try motoring when waves are over 1m high.

Calm water, no current, Maximum of 3500 RPM @ 7.9 knots IIRC.

BTW, I calibrated the tach with an optical tachometer.

Having changed the alternator, it was way off.

Steve B. wrote:Yesterday I installed a new Varifold 15 x 13 RH two blade prop.
The difference in motoring was remarkable to say the least.
I can still just achieve max rpm with the engine, but I can also get 5.5 knots motoring speed at only 2000 rpm.
There's still a little vibration between 2200 and 2700 rpm, but not as bad as before, although now there's no real need to run in that range.

The Varifold needs a quick shot of forward to unfold it.
Just putting it in reverse will not unfold the blades most of the time.
It's something I'll get used to.
Overall, I'm a happy camper.
Rick Steadman of Varifold was very helpful.

Steve B.

Any problems getting it to open in reverse?

Unlike the Gori it replaced, I have to drop it into forward and immediately go to reverse to get it to open in reverse. If I'm moving forward at all, it will immediately fold.

Going forward, it opens immediately every time.
I just have to remember that reverse is (fwd idle), then immediately go to reverse.

Overall, I'm satisified with it.

Steve B. wrote:Unlike the Gori it replaced, I have to drop it into forward and immediately go to reverse to get it to open in reverse. If I'm moving forward at all, it will immediately fold.

Going forward, it opens immediately every time.
I just have to remember that reverse is (fwd idle), then immediately go to reverse.

Overall, I'm satisified with it.

I had the same issue with it, which is why I asked. I didn't think that was acceptable, and they exchanged my blades at no charge for a slightly different configuration that would open reliably in reverse.

You might want to do the same... I don't think someone should need to know "the secret technique" to get the boat to stop or go into reverse. (Stop is the major issue in my view.)

Thanks for that info. I was just getting used to the fwd/rev thing, but
I'll contact them and let everyone know what they say.