prop size

[mustang49]

Can anyone tell me the best prop size for my Mac26x. I have a50hp Honda motor

[Irafatsar]

One would think that the macgregor factory would be able to provide the best prop/engine information.

[ROAD Soldier]

11 3/4 x10 for Honda 50HP on the Chesapeake Bay it allows full RPM, accelleration, and speed for this environment. I have access to Saltwater, Brackish Water, and Fresh Water Here and the Prop works great in all water types. The only environment I could think of maybe changing to a different prop would be high altitude environment. Less air pressure equals less HP no matter if you have Carbs or Injection. The only way to combat that is turbos or superchargers.

[Divecoz]

One would think that the macgregor factory would be able to provide the best prop/engine information.

Too many variables .........engine makes for one and sizes/HP, for another ( no less than 6 popular 50HP Motors . Then add the 60s and 70s 75s and 90s and 135's add 2 smokes and 4 strokes to the mix.) and varying loads for another.......... Its guess and by golly molly and a lot of reading and asking.......

[Divecoz]

One would think that the macgregor factory would be able to provide the best prop/engine information.

Too many variables .........engines for one and sizes for another ( no less than 6 popular 50HP Motors . Then add the 60s and 70s 75s and 90s and 135's add 2 smokes and 4 strokes to the mix.) and varying loads for another.......... Its guess and by golly molly and a lot of reading and asking.......

RoadW states above he has a Honda 50, with the small prop and I have the Merc 50 with the Big Foot . We both run 10 degree's of pitch though , while I run a 14 " prop and he runs a 11 3/4" prop.

[jaguar496]

Can anyone tell me the best prop size for my Mac26x. I have a50hp Honda motor

look up http://www.piranha.com. this site has a questionaire that will give you the proper prop size; of course, will also entice you to buy their product. stew of "THE RESTLESS TWO"

[RocketsCrew]

I use a Solas 12X3X9 for a Yamaha f50 and if the Honda specs are similar, then this prop might work for you.

[Ivan Awfulitch]

I use a Solas Alcup 11.8 X 9 4 blade on my Honda 50. Does allow me to run WOT at about 16 knots, but gives me better slow speed control in the marina compared to the 3 blade that came with the boat.

[trip01]

Ivan,

I am interested in what your revs are at WOT with the Solas Alcup 11.8 X 9 4 blade. What are other pros & cons with the 4 blade


I have a Yamaha 60hp 4 stroke (13 tooth spline) on Mac 26M. Currently using a 11 3/8" x 12" and getting 4300rpm at WOT.

Want 5000 - 6000rpm at WOT.

Solas advises;
12 1/4 x 9 is what your meaning 13 spline and ideal for your water ballastted mcgregor (IE 12 1/4" is the Diameter & 9" is the pitch)

What you are far better of with and we would be the only one in the country with these is 4 blade aluminium...

11.8x9 or 4x 11.8x10

I understand that the 4 blade provides better control at low revs. The lesser pitch will me higher revs at WOT. I would like to try the 12 1/4" x 9 (3 blade) & 11.8" x 9 (4 blade) for comparison.

Kind Rgds
Dave

[milest]

hi,
I have been reading for so long.First, thank you all for mod pages and forum posts,I've learned a lot.I have a carburated 06 honda bf50a.I tried to switch from solas 12.1x3x9 to 11.8x3x11. You never ever do it.The prop is singing between 1500 and 3000 rpm and with very little thrust,5300 rpm at WOT.A service guy told me the best choice would be 12x3x9 "stainless" one.But to go 4 blades is a good idea, docking will be much easier for sure.Sorry for my english

[Terry]

I have measured the radius distance frrom the center of the honda BF50 spline to the anti-cavitation plate and I am positive it is barely 6.25 inches, so a 12.25" diameter would be almost hitting the anti-cavitation plate, it is too big a diameter for a Honda BF50. You need a bit of space between the edge of the prop and the anti-cavitaion plate, enough space to keep the prop submerged during a turn. An 11.8 diameter would be the largest diameter you want. A 4 X 11.8 X 10 Solas would be ideal for the BF50. I have a Solas Alcup 4 X 11.4 X 10.75 on my BF50 and I get 5600 - 6000 depending on full or empty ballast. I had to get my Solas repitched at a shop to get the 10.75 pitch. I am not sure you can still get the Alcup but the Solas Amita is still available. The SS props are far too expensive. The 4 blades will get you on plane sooner and your mid range speeds will be better and low speed control will be better but top end speed will suffer due to the extra drag from the fourth blade.

[trip01]

Going up to Warana day after tomorrow to purchase a 4 blade 11.8" x 9" prop. $240 (aus)

Replaces an 11 3/8" x 12".

Expect WOT to go from 4300rpm to approx 4800rpm (allowing 200rpm for each inch diff in pitch, less a bit for the larger diameter)

Plan to take the Mac out on the WE. Stay tuned for report on the outcome.

Kind Rgds
Dave

[opie]

milest,
Can you explain what you mean by "singing" around 1500 rpm and higher? I have not heard of anyone else having this problem with Solas except me. I tried a Solas 4 blade and I have a "singing" sound between 1500 and 2000 rpm. It is so bad, I took off the prop after 3 minutes of use. Strange, I think.
Opie

[Erik Hardtle]

(past posting below)

I searched around the board for the best props and decided on the 9 pitch, so I purchased the Solas and Vortex.

I just recieved my two 4 blade 9 pitch props for my Honda 50 hp 4-Stroke. I used to use a 13 and 11 pitch (9 - 11 kts @ 5800 rpm) . So here are my results.... keep in mind I have a 138 lb centerboard mod, 2 gel batteries, an engel refigerator and two 9 gal gas tanks. I left the ballast tank empty:

Vortex 4 blade: 12 x 9
5000-5500 rpm - 13-14 kts

Solas Amita 4 11.8 x 9
5900-6000 rpm - 15-16 kts
part # 3313-118-09

Ok so the Solas rocks and I will keep the vortex for a spare. I didn't have any cavitation, probably because of the extra weight on my boat. At lower rpm's it does a little "singing" but not so much that it bothers me.

Added: I got the props from iboats.com

Erik Hardtle
Knot Shore

[milest]

hi opie,
This "singing" around 1500-2000 rpm is because of high pitch for heavy macs.My is preety heavy with ref,250 lb. fresh water tank,130 lb. daggerboard , dingy and 3.5 hp. Tohatsu 2 stroke outboard.May be 4 blade 12.1x8 prop is the solution? That service guy told me SS props don't flex as the aluminium ones and that fixes those cases and 3X12.1X9 SS was his advice.