F32 props

willietrojan · Post by **willietrojan** » Mon Jan 21, 2008 4:44 pm

Is anyone running 15" props on their F32, I found good deal $$ on a pair of
15X15. Not sure what it might do to the performance?

rossjo · Post by **rossjo** » Wed Jan 23, 2008 9:39 pm

depends on engines and transmission ratio, but 15x15 should work well.

I'm running 17x20's through direct 1:1 Velvet drives with 220HP Cummins 6BTAs @ 30 knots.

obeejr · Post by **obeejr** » Thu Jan 24, 2008 9:50 am

I'm running 16X15s and I need a lot more rpms at cruise compared to when I used 16X16s.

I used to cruise at 3100 rpms doing 17.5 to 18 knots with the trim tabs down. I need to turn 3350 to make the same speed with the 16X15s. My guess is the 15X15s will need about 3500 rpms to do the same speed.

The real key is wide open throttle. If you are getting around 4200 WOT, your props are perfect. If you get over 4400 or less than 4000, you need to change props.

I'm going back to the 16X16s this season.

wowzer52 · Post by **wowzer52** » Sun Feb 03, 2008 1:26 pm

I am running 15x15 props on my F32 w/351's and turn 4100 rpm at 28 knots with four full fuel tanks. perfect.

obeejr · Post by **obeejr** » Mon Feb 04, 2008 1:15 pm

wowzer52-

I have Crusader 350s. Maybe they need bigger wheels than your 351s.

willietrojan- What do you have for power?

wowzer52 · Post by **wowzer52** » Mon Feb 04, 2008 1:51 pm

The standard way to check for the correct prop size is to run the throttles wide open in calm water. If your RPM's are between 4000 and 4400 then they are just right. If the rpm's run below 4000 at full throttle you need to go smaller, either pitch or diameter. This will allow the engine not to lug. However, if the rpm's run above 4400 at full throttle, you need a larger prop, either pitch or diameter, or both. A full, loaded boat should run close to 4000 and a lighter, empty boat will run closer to 4400. I do not run my boats this hard at any time other than to check the correct prop size. I like to think that less strain equals longer life. Kind of like marriage.

Stripermann2 · Post by **Stripermann2** » Mon Feb 04, 2008 2:15 pm

If nothing else and the price is right, just take them and keep on the boat.

I now have a spare set- 16X16, in case I damage them while away and need to have them installed. Sure beats waiting for a repair when trying to get home...

willietrojan · Post by **willietrojan** » Mon Feb 04, 2008 3:13 pm

That's most likely what I'll do. What cruising speeds to you get and where do
you boat? It look like you have quite a Trojan fleet at your marina.

Stripermann2 · Post by **Stripermann2** » Mon Feb 04, 2008 3:19 pm

On the Potomac, just below the 301 bridge.

I cruise at 18-21 kts. 3,000-3,100 RPM w/ ideal sea conditions.

willietrojan · Post by **willietrojan** » Mon Feb 04, 2008 7:49 pm

I'm on the Yeocomico River just below Coles Point, I dock at White Point Marina. Small World

Stripermann2 · Post by **Stripermann2** » Tue Feb 05, 2008 8:29 am

...I'm up in Colonial Beach.

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