Folding Prop

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Folding Prop

Postby mike cunningham » Thu Feb 01, 2018 11:46 am

I realize I am resurrecting a topic which is subject to endless debate but I am on the cusp of a haul out to deal with a leaking shaft seal and would like to make some decisions about underwater stuff so I can get all work done on a single haul out,

I currently have a two blade fixed prop on my F30. Have had the same prop since purchase 19 years ago. As far as I know it has been performing well. Max speed in calm water, clean bottom is about 6.2 Kts, Max RPM about 3400 RPM (never run that high for very long). Decent, not spectacular, performance in a headwind/seaway. To the extent I have tested in rough conditions, I have been able to make decent headway under power.

I say "as far as I know" because I have nothing to compare it to. I believe the top speed and RPMs are pretty well lined up with what I should be expecting out of a 2GM20F in a 30 foot Freedom.

So, in order to improve light air performance, I am looking at a 15X10R flexofold two blade folding prop as a replacement for my current fixed blade. Reviews are generally positive and price quote is reasonable. Three blade Flexofold almost doubles the cost so the two blade is my target. The big questions are:

1. Am i really going to see any useful performance improvement, in particular, light air performance which is less then stellar as many of you know? I have never tied to align and mark the current prop to minimize drag. Not sure alignment with keel and rudder would really help much given the location of the prop but maybe someone has some experience with doing this.

Is there a less expensive less mechanically risky way to get a performance boost in light air? One thing about a fixed prop, it is pretty foolproof.

2. Does anyone have a Flexofold fitted to a Freedom and, if so, any observations?
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Re: Folding Prop

Postby gamayun » Thu Feb 01, 2018 12:55 pm

We seem to be on the same trajectory! I put a 3-blade Max prop last year. I haven't taken measurements under sail but it's supposed to give me a half knot increase in less drag (I forget how I came up with that #). I seem to have a little better propulsion under motor primarily the reason I went with 3 instead of 2 blades. The biggest thing for light air and bigger bang for your buck is to get a good reacher. I just got one from a friend so haven't tried this but my research indicates this would be the way to go. As with much of my experience, it is not deep and informed by what I read so your mileage might vary ;) Would be curious what others think.
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Re: Folding Prop

Postby mike cunningham » Thu Feb 01, 2018 5:27 pm

That is my dilemma. Maybe I would be better off rigging for a reacher and just forget about trying to max out performance hard on the wind.

You know exactly what I'm talking about when you are near becalmed while the fleet decimates a lead you worked for three days to develop.

Regarding speed improvement with the feathering or folding prop. I have also heard as much as a half a knot. I just wonder if anyone has any real wold experience achieving this. I believe the advantage begins to tail off as wind speed increases but not sure if that is correct either.
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Re: Folding Prop

Postby Camino » Thu Feb 01, 2018 11:29 pm

Mike and Carliane

I’m really trying unsuccessfully to cut down my online time :twisted: but maybe for lent :D Except for the ditch run (this yr will be no 7 for me ) in cruising class, motor allowances aren’t given :D Carliane has a good point. My last boat had a folding Martel (spelling) bronze 2 blade prop. Once way out I lost one of the blades! I could and did idle back to Emeryville under sail . $$. This boat has a thre blade feathering max prop- seems good. Don’t know about advantages in speed however. An assym reacher or smaller fractional thing off a smallish bowsprit would be nice I think. Winter dilemmas!
Last edited by Camino on Fri Feb 02, 2018 11:51 am, edited 2 times in total.
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Re: Folding Prop

Postby rvivian » Fri Feb 02, 2018 12:46 am

Hi Mike -

I don't race, but I need to move in the light airs we have up here (mostly below 10 knots most of the day.

Haarstack sent me the following specs for an F30 Top Reacher before he sold out"

FREEDOM 30 (MULL)

155% TRIRADIAL "JIB TOP/CODE 0" REACHER
LF = 29.0' LP = 15.24'
AREA = 223 sqft
CLOTH = "CZ30 HP" = 2.2 oz laminate with a 1500 black Aramid warp & a 40x40 ripstop taffeta.

The following is a list of equipment you will need to fly this sail.
1.) 2 sheets for the clew, each one ~ 60 feet
2.) Turning blocks for the sheets (snap shackles to the aft stantion base- behind the cabin)
3.) Raise and lower the sail using an "ATN" or a "ChuteScoop", or a detachable single line roller furler.

I ordered a Top Reacher for Heart's Desire after posts by Hans and Dale (you can find them on the site). Even though I sent him the specs and a picture of Dale's sail underway, the locak sailmaker delivered a sail labled "drifter" that is a kind of low cut deck sweeper with the tack set on the gunmount tube. It does improve the sailing speed by around a knot in winds below 10 -12 knots.

As to a shaft seal I now have a custom cut Tides Marine from Paul Dennis.
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Re: Folding Prop

Postby mike cunningham » Sat Feb 03, 2018 3:32 pm

Thanks for the sail info Heart's Desire. I have given some thought to a reacher. My storm jib sheeting set up could easily double as a sheeting arrangement for a reacher.

Assuming the sail was tacked to the gunmount, the LP implies one would have about a 7 foot overlap, does that sound about right? On my boat the mast to gumnout is around 9 feet.

In late 2015 I purchased a gunmount, pole and spinnaker from a fellow on the board with the intention of using it for the 2016 SHTP. The system was originally mounted on his F32. Although the pole and chute are bigger than the original F30 spec, the gunmount is probably near identical to what was delivered on the F30.

I fitted a new re-enforced pulpit (also purchased form someone on the board). I never had the time to rig the system much less practice with it. The pole is major reason I did not proceed. It is an absolute monster! Although it is two feet longer than F30 spec (18 vs 16 feet) even if I cut two feet off it would still be a monster. It is a 4 inch diameter 1/4 inch wall aluminum pipe. The dang thing weighs 50 pounds! Having this thing hung on my stanchions in a heavy seaway was not appealing. Attempting to maneuver the thing forward and aft just seemed like it would be way too difficult. This feeling was only amplified during the race. When sailing deep in 20 Kts I notice the bow tends to dig in. I assume this is due to the location of the mast combined with the dynamics of downwind sail pressure. In a following sea this bow down tendency can be a little alarming. I never had any issue but I would be loath to add any fixed weight forward. The anchor and chain were all stored in the aft cabin. The forward cabin was full of empty diesel jugs and not much else.

I am mentioning all this because I had often thought the pole could do double duty as a reacher sprit if properly set up. Problem is the weight, bulk and maneuverability issues. I have a couple of two part carbon windsurf masts in may garage. taking the lower straight section from one of these masts and laminating a tapered upper section on each end would yield a 16 foot pole of about one fifth the weight of the aluminum monster. To boost strength I thought I would laminate several carbon fiber sleeves over the assembled pole, adding to weight, but not by too much, and giving me a strength boost which might get the carbon pole close to the aluminum.

If I was successful then I suppose I could rig the gunmount spinnaker as per normal albeit with a much lighter, easier to manage, pole.

If one were to swing the pole near parallel to the boat and move the pole back such that it contacts the mast, then one could fasten the pole to the mast in some structurally safe manner and use the remaining pole extension forward as a sprit. As mentioned earlier, I have about 9 feet from gunmount to mast, so the sprit would extend something like 5 feet from the bow with exact extension depending on how I secure the pole to the mast. This would be a light air only set up.
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Re: Folding Prop

Postby rvivian » Sat Feb 03, 2018 8:49 pm

Hi Mike -

I just went the 1/2 mile down to Heart's Desire and back to measure because your 9' measurement didn't seem right for my F-30. It was time to check on her anyway.

The distance between the front of the mast and the tab on top of the gun mount is right at 11 feet. (F-30s vary that much?)

I once rigged up my gun mount (pole, sail and lines at the dock) to see how it works, but I've never flown the spinnaker underway. From what I've read on this site the pole is carried with the front end in the gun mount tube and the aft end in the lifeline clip while underway and rigged. In some of the diagrams there is a system of lines and blocks that allow the pole to be extended and retracted through the gun mount from the cockpit.

I think that you should PM Rick Simmonds or at least search his posts on this site-- I think he is a gun mount advocate and uses it very frequently.
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Re: Folding Prop

Postby mike cunningham » Sun Feb 04, 2018 8:16 pm

rvivian wrote:Hi Mike -

I just went the 1/2 mile down to Heart's Desire and back to measure because your 9' measurement didn't seem right for my F-30. It was time to check on her anyway.

The distance between the front of the mast and the tab on top of the gun mount is right at 11 feet. (F-30s vary that much?)

I once rigged up my gun mount (pole, sail and lines at the dock) to see how it works, but I've never flown the spinnaker underway. From what I've read on this site the pole is carried with the front end in the gun mount tube and the aft end in the lifeline clip while underway and rigged. In some of the diagrams there is a system of lines and blocks that allow the pole to be extended and retracted through the gun mount from the cockpit.

I think that you should PM Rick Simmonds or at least search his posts on this site-- I think he is a gun mount advocate and uses it very frequently.



I stand corrected on the distance. I measured it once but not recently, my 9 foot distance was a guesstimate. Should have made that clear. I'll remeasure mine today just to confirm we are essentially identical.

I actually had the gun mount on a wingmast Freedom 25 I owned back in the 80s. I never used the sail but was familiar with the rig and the pole mounting. Some time ago Rick Simmonds was kind enough to send me his rigging and flying instructions so I have those ready to go.

BTW, the Aussie guy who bought the F25 from me (boat was in the Seychelles) broke the wingmast under spinnaker in 20Kts when the running back parted. The F25 carries the spinnaker at the mast top unlike our boats. Cost him a fortune to get a replacement round mast buit and shipped half way around the world.
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Re: Folding Prop

Postby hotstonp » Wed Feb 07, 2018 6:29 pm

Hi Mike

I sail a UK version of the F32 (an F33) with the Hoyt Gunmount and I do use it. Mine was the first one built in the UK and they didn't get a couple of things quite right and now the pole needs some replacement parts to slide properly but it is still a brilliant way of flying a kite.

I quite happily sail on my own through the Solent with the kite up and it is easy to hoist, set, gybe and douse. The rigging looks complicated when you first have a look at it but once it is all set then it is very easy to use and can all be done from the safety of the cockpit.

I keep the kite in a bag along the rail ready to go. There have been some postings on making a GRP mouth for the kite launch - which would make it even easier to get the kite back down and into its bag. At the moment I just have a shaped canvas mouth to the bag and it normally does the trick.

One photo with pole and kite stowed
170409 FERONIA GBR3805L 1Y3A1235 (3).jpg
170409 FERONIA GBR3805L 1Y3A1235 (3).jpg (172.49 KiB) Viewed 893 times


And another with kite up
IMG_3130 (1).jpg
IMG_3130 (1).jpg (210.99 KiB) Viewed 893 times


You've got me thinking about a reacher though...... mmmm

Have fun
Peter
1986 Freedom 33 Cat Sloop (UK Hoyt), Hull # 001, Aluminium Needlespar rig, shoal keel.
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Re: Folding Prop

Postby mike cunningham » Thu Feb 08, 2018 8:39 pm

Those are some excellent spinnaker photos and very helpful. Also helpful is your review of generally positive experience with setting and dousing. I had some concerns based on comments some users have made about having, or at least wanting, to use a spinnaker sock. I would like to avoid a sock if possible.

In the first photo, is that a preventer you have rigged to the camber spar? I tried this on the Hawaii sail and I was concerned about the stress on the rig due to the acute angle of the preventer. I subsequently removed it. Given what happened to the camberspar after I removed the preventer, I think I should have stuck with it. Assuming that's what it is , what has your experience been in heavier downwind conditions?

Sorry, after looking more closely at the photo, the line looks like your sheet, not a preventer. However, this brings up another use for the gunmount sprit. Assuming you had a fixed attachment point four or five feet out front of the gunmount, you could probably rig a camberspar preventer with a much less acute angle.
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