Folding / Feathering Props

[tburgess]

Thanks for the thought but I drop them into reverse and back to neutral all the time. After sailing for a while they start spinning again and I have to repeat the process....and around and around I go. Very frustrating on a multi day passage. Inevitably they lock in reverse and I have toruble starting them later.

[guxiangdeyun]

is everyone can supply some links to propeller calculate

thankyou

[vacendak]

an excellent opinion about AutoProps from the guy I trust:

I don't like the Autoprop. It is ugly and I don't believe their claims about being low drag under sail.
Those props have been known to generate enough drag to start the engines on fast catamarans

2 guxiangdeyun: almost all producers supply such calculation for free (online)

[Hud3]

Originally Posted by tburgess

...Locking my engines in reverse folds the props and stops freewheeling but the Yanmars get stuck in reverse even though I shift back to neutral. This causes starting problems after we sail for a while. I confirmed this starting problem (transmission locked in reverse) with Mack Boring but they are not offering any good alternatives to help fold the props.

I have a Yanmar 4JH3(B)E, and put it in reverse when sailing. It won't shift back to neutral until the boat is slowed to almost full stop. And the engine wouldn't start unless it was in neutral.

The way I got around that was to defeat the interlock switch that prevented the engine from starting. You can rearrange a couple of wires behind the instrument panel, and ***voila*** it starts in reverse. Shift quickly to neutral and you're good to go.

[rgm.nz]

Hi Totem
Do you have that flexofold prop on yet and had time to try it ? Very interested in how
that works for you .
RGM

[svTOTEM]

RGM - I meant to post back about our Flexofold, but have had a few distractions lately. We (wife and 3 kids) moved onboard at the end of May. It's all gone really well and the kids love it, but WOW is it a challenge getting through all the junk we accumulated over the years. We will depart from Puget Sound on 8/21 - first stop San Francisco.

The flexofold is excellent! It has more then met my expectations. I'm fairly certain that the old prop (Martec) was not spec'd right for the boat/engine; however here is the short list of differences (engine is Yanmar 4JH3TE):
1. Increase in top speed from 7.1 to 8.4 knots (3450 RPM). For sake of comparison, and not debate, I know of another Stevens 47 with the same engine and a MAX prop that tops out at 8.2 knots.
2. At 7.1 knots now (about 2600 RPM) I burn at least 30% less fuel then before - this is huge.
3. There is less vibration and noise when motoring (likely indicates the old prop has problems even though on inspection there was nothing obviously wrong).
4. I've not sailed enough with it yet to say that there is a gain in performance - though looking at the 2 props side by side and Flexofold has a significantly smaller footprint.
5. It was very simple to install.
6. In reverse - I clearly have less power then before. So far I find this translates to mean I use higher RPM to acheive the same things as before. That said, I find absolutely no problem manuvering in reverse.

Chuck Angle, the Flexofold distributor, was very helpful in spec'ing out my prop. I have no conection to Chuck or Flexofold; I do know one of the owners of PYI, the distributors of MAX prop. This weekend I plan to dive and inspect the prop (along with other bits and pieces). If I find any issues with it, I'll pass that info along next week.

[rgm.nz]

Thanks Totem
I have kept an eye on the flexofold site . Lots of good solid gear comes out of OZ & NZ .Been hoping to meet someone with one of these on their boat . You are the first so really appreciate hearing from you . What is your engine HP & gearbox reduction ratio ? And what size prop /pitch did you end up with ? I know about the other specs necessary to match prop with boat . Just wanted to get an idea as your boat is not far off , size wise ,what I may end up with .
RGM

[svTOTEM]

RGM
Engine: Yanmar 4JH3TE, 75HP Turbo
Gearbox reduction: 1.62
Prop: 20" x 12"
Last weekend we took the boat from Puget Sound, through the Ballard Locks and Lake Union (with 6 bridges), to Lake Washington. Needless to say to say, there was lots of boat handling. It all went great - the prop is great.

Jamie