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  Topic Review (Newest First)
06-09-2014 08:50 PM
Re: Any PSC37s with 4-blade Variprops out there?

Dave are you and Sherry getting ready to leave on your voyage soon?

Megan's Island
10-17-2012 08:55 PM
Re: Any PSC37s with 4-blade Variprops out there?

I am not sure what the presets were when the Vari-Prop factory set it up for us. I do know that the order was as follows:

DF-1 07
VariProp DF-107 hub 4-blade RH 18"x14"x12" for 1" SAE shaft
Pacific Seacraft 37
LWL 27'g"r displacgment 16,200 lbs. Yanmar4JH2-E 51hp @3600, 2.62:'1 reduction, RH rotation, 1" A22 shaft

The concern was whether the 1" prop shaft was made of Aquamet 22 vs 316 stainless. It turns out it was the higher quality Aquamet 22 and the Prop being speced as a 4 blade would work. Rick Steadman came to our boat and did the measuring to determine the appropriate size and configuration. This is what he reported:

According to the computer for a vessel of 16,200+ lbs. with 51hp the shaft size should be 1-1/8” if standard 316 stainless steel. A 1” shaft should be the higher strength Aquamet 22 alloy or equivalent. 316 stainless and A22 visually are the same so I do not know how we’d determine if your shaft is the higher strength material or not without documentation from Pacific Seacraft or a metallurgical test.

The shaft presently has ¼” more length beyond the end of the bearing than is specified by ABYC standard. I measure 1-3/4” between the end of the bearing and the start of the taper. ABYC calls for 1.5 X shaft diameter as the maximum. If you are to fit the VariProp I recommend shortening the shaft to meet the current ABYC standard.

The shaft and aperture configuration has sufficient opening for the length of the VariProp when installed however since the opening is not enlarged by swinging the rudder to the side I think that for installation of the propeller either the shaft will have to be moved forward and then inserted into the propeller once the propeller is in the aperture or the propeller will need to be disassembled and reassembled on the shaft.

This doesn't answer your question on pitch but the Variprop people did the figuring for me and I decided to not second guess their calculations.

Curtis Smith

s/v Cilantro
PSC 37 yawl
10-16-2012 08:30 AM
Re: Any PSC37s with 4-blade Variprops out there?

Nice job on the install. I contemplated cutting the shaft when we put ours in but chickened out. Out of interest, do you know what the factory preset your forward and reverse pitch to? After much discussion we went with 12" forward and 9" reverse. On a somewhat different note, I went to a seminar by Larry Berlin from Mack-Boring at the Annapolis show and he had a very interesting insight into the whole propeller pitching process. Basically, for reasons I didn't fully grasp, the tach on the engine panel although reasonably precise is not accurate enough and he suggests using a photo-tach to determine the true rpm of the engine and we are not to be surprised if the difference in the readings is as much as 200 rpm. Same comment applies for the boat speed instruments..... I think I'll have to get hold of a photo tach and create a variation curve and check my knotmeter against the gps if I really want to be accurate about all of this. As usual, nothing is as simple as you think.

Fair Winds
10-16-2012 12:26 AM
Re: Any PSC37s with 4-blade Variprops out there?

We too ordered a Variprop DF-107 4 blade prop for our 1998 PSC 37 & had it installed this summer in Maine. The prop has a massive hub & is well engineered well. As new owners we didn't have any experience with the existing 2 blade 18" prop & the Variprop went on before we launched. The prop install was part of our refit that included adding a PSS dripless shaft seal, new engine mounts & a new cutlass bearing. So the Yanmar JH2E was lifted & the propeller shaft removed to be cut down & re-keyed. The shaft was shortened about 1.875" and the goal was install the new prop so that it could be removed in the future in case of damage without pulling the engine or rudder. The prop aperture was ground back about .75" where the cutlass bearing is so we could also install a Spurs Line Cutter.

The performance under forward & reverse is exceptional & there seems to be minimal prop walk. The max rpm in forward is 3450 but we didn't have all our instruments working to get speed data to know definitively the max boat speed.
10-02-2012 08:41 AM
Re: Any PSC37s with 4-blade Variprops out there?

on the engine rpm. the engine should be able to come up to the max rpm .per the engine builder. the prop pitch should be set to let it do that. check with the engine dealer in your area.
10-01-2012 06:41 PM
Re: Any PSC37s with 4-blade Variprops out there?

We thought it was time to give an update. Mythago was outfitted with a Variprop DF-107 4 blade 18” X 12”(forward) X 9” (reverse) this last spring. Installation did end up requiring the rudder to be dropped to the point that there was bare rudder post behind the prop shaft and at that point the VariProp just squeaked on. On sea trial, we were able to get up to 3100 rpm maximum and we were seeing hull speed at around 2600 rpm which according to Dave Gerrs propeller book calculations is about right. If necessary, you can adjust both forward and reverse pitch in the water but I'm glad it didn't come to that. A couple of the significant differences over the old 3-blade ProWell prop... this one is much better balanced and smoother running, and, going from one gear to the other the new prop doesn't make a "thump" when the hub hits the stops. We did try a crash stop from 7 knots and there wasn't any problem. With the 4 blades, we slowed very quickly without a lot of commotion which was a great improvement over this props predecessor. The Variprop has a "Soft Stop Multi-Disc brake" built into the hub to minimize the impact on the stops and I'd say it does make a difference and maybe that will pay off in greater longevity?. As for Prop walk, it's still there but is signficantly lessened in routine use. Having the 4 blades allows the same power transmission into the water at a lower rpm which to me makes sense in that less lateral movement is created. Add on the power in reverse and the walking tendency increases noticeably. All in all, we are happy with the purchase. It doesn't seem to have made any real difference in fuel economy but we are confident that we can get all of the power of the engine into the water now when it proves necessary. Thanks to everyone for their thoughts and observations.... this is an awesome group!
01-24-2012 05:37 AM
unomio We have a 4-bladed Variprop, the DF107, which is a 19" prop that Variprop cut down to 18" to fit the aperture in our 2006 PCS 40. We specified that propeller for that boat, which we had Pacific Seacraft build for us. We went to a 4-bladed prop for the reasons you mention: less cavitation in heavy weather, more surface area, etc. We were also sold on the ability to change the pitch of the Variprop while still in the water, without having to pull the boat out. The Pacific Seacraft factory worked with the Variprop distributor's rep to arrive at the appropriate propeller diameter and pitch for our boat. Once the boat was in the water we got the 3000 RPM redline at full throttle on our Yanmar 4JH4e, which indicates the pitch setting recommended by the prop rep was just right; we have not adjusted it since. In passing, I should mention that we had a two-bladed fixed (factory installed) on our 1983 PCS 37, and we used that for 23 years without a problem, either with maneuverability or in powering into head seas. Four blades may be more than you really need for the 37, based upon our experience. For the PCS 40, however, we consider four blades an absolute necessity. We've been happy with the Variprop and with the customer service they provided while the boat was being built. I'd suggest you discuss the issues you have with the Variprop rep and possibly with Pacific Seacraft. The guy we worked with was Rick Steadman at Varipropeller, USA (VariProp USA - The best feathering and folding propellers in the world!).
01-10-2012 08:15 AM
Minnewaska I have a max prop and love it. Built like a tank. A recent thread was inquiring about vari-props and very few seem to use them. It provoked me to search a bit and most of what I saw was discussion about the reliability of the vari-prop internal mechanisms. I just disassembled my max-prop to return it to have a ding in one blade repaired. Service folks on the phone were excellent at max-prop (PYI, inc). The internal gears looked brand new and the stop is an internal brass lug that showed no wear after 6 years.

I've never used a vari-prop, let alone seen one installed (that may say something itself), so take this for what it's worth and research you're own conclusion.
01-10-2012 07:47 AM
Mythago The Variprop version is machined more accurately internally, has externally adjustable stops for adjusting pitch and the blades are of a different shape with a greater and more efficient cross section. The principle of how they feather the blades is the same.

Our 37 has 97 mm between the end of the prop shaft and the front of the water so, without disconnecting the shaft coupling or dropping the rudder, that is the space I have to get a prop on. The end of the shaft is tapered so initially the prop doesn't have to be straight. To get the prowell off/on, I have to remove the anode and separate the front and rear halves of the hub and literally take the prop off in pieces. Putting it back together, you just have to make sure the blades go in with the same relative position or the pitch on the blades is not consistent. The first try took more than a couple of attempts.

Talking with the MaxProp rep at the boat show, he expressed concern that I couldn't get the prop on without a lot of work. Same goes for the cheaper VariProfile prop. Why does it always work out that the best option is the most expensive???
01-09-2012 06:16 PM
Originally Posted by Mythago View Post
Hi, folks....

. Prowell is long gone now but apparently their technology was acquired and refined by Variprop. To make a long story short, the stops in the hub of this thing wear and need to be built up every other season, pitch is not easily adjustable (requires welding or filing the stops) and there are some cracks in the blade root of one blade.... so, it is time for a replacement.

At this point we are considering going to a 16" 4-blade feathering Variprop. Plus, the hub on the Variprop is short enough that we can get it on the shaft without taking off the rudder.

Dave and Sherry
Hi Dave and Sherry,
I cannot give you the information that you are looking for but I have a few questions.

What refinements did Variprop make to solve your previous problems?
I was not aware that the rudder had to be removed to install some feathering prop, do you know if that is true with a Maxi-prop?

I am considering installing a feathering prop to replace my 2 blade fixed and am in the beginning stages of doing my research.
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