I'm swinging a 14x14 7/8"RH Martec 2 blade folder with a Universal 25xpb engine and standard tranny. I think the reduction is 2.05:1.
I got the same from Chuck Angle from Flex-I-Fold in 2003. No prop he would recommend. Lately I've been thinking I could increase the pitch to 15. I cruise at 6.4 kts at 2450 rpm and can get 7.0 at Max rpm of 2900 with no smoke or laboring. Hope this helps. Dennis C, Touché 35-1 #83 Mandeville, LA Prop works Sent from my iPhone > On Nov 9, 2014, at 8:59 AM, Carl Gerstle via CnC-List <cnc-list@cnc-list.com> > wrote: > > Having searched the archives and not found this info, I feel the need to > ask... > > I am committed to a re-power this winter and am surprised at the difficulty > in choosing an appropriate prop which then leads to the appropriate engine HP > and transmission choices. I already have input from two other 35-1 owners but > am looking for a wider array of input. My old engine/tranny/prop is the > venerable Atomic-4, 1:1 tranny, 12x6 folding prop. The new engine will be a > BetaMarine... but either 20 or 25 HP depending on how much power a prop that > FITS can absorb through a choice of a 1.45:1, 2:1, or 2.6:1 transmission. > > As I really don't want to face the added expense of upsizing the shaft from > 7/8" to 1" (even a 14" prop can be safely driven on a 7/8" Aquamet shaft) or > worse - moving and replacing the strut to gain prop diameter - please provide > whatever real-world info you have on the prop (make, diameter, pitch); engine > HP, and transmission ratio that you are using on your 35-1. > > It turns out that the prop make/model is critical due to the effective hub > length. For instance, my current folder places the blades 5 5/8" behind the > strut (5" hub, with 5/8" exposed shaft). The prop I am considering (Flexofold > 13") has only a 4.5" hub length, while a Martec 14" appears to be a beefy 9" > from hub to blade pivot. So the length of the hub has a large effect on tip > clearance. As Dave Gerr (The Propellor Handbook) recommends an absolute > minimum of 10% clearance (a 14" prop thus needs 7" + 1.4" clearance from > shaft center to hull) - I only have 8" clearance with a 4.5" hub) - a longer > prop hub allows for greater prop diameter (a very good thing). So real-world > experience - including your experience with speed, prop noise, and vibration > from using a small blade tip to hull clearance would be invaluable to me. > > The problem is complex enough that Flexofold actually refused to recommend a > prop, tranny drive ratio, and HP requirement; and recommended that I work > with a boat-builder to work out these choices. > > Your actual numbers and knowledge will be greatly appreciated. > > Thanks, > Carl Gerstle > Impulse > C&C 35-1 #149 > Portsmouth, RI > > _______________________________________________ > This List is provided by the C&C Photo Album > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go bottom of page > at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > _______________________________________________ This List is provided by the C&C Photo Album Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com
