4 Blade Propco Slingshot Prop For My DF225?

[seaox230c]

700 bucks is a ton of money for a prop...hill marine makes some excellent 4 and 5 bladers for 300-400...Excellent bite-good speed...universal merc or Michigan hub

[Moonlighter]

So here's the deal. I gave the motor 4 runs and took video on all runs. The first couple of runs clearly indicated that the motor was sitting too low even after trimming a little.

What I did on the 3rd run was instead of watching my trim gauge, I kept trimming up as I watched my speed on a phone app. At WOT, When the speed leveled off, I hit 45 mph and 5800rpm. Bingo. When I looked at my trim gauge, the needle was above the half way mark almost to 3/4. I was shocked as all my gauges are new and wouldn't think of trimming that high. When I went to the back of the boat the plate was properly just above the water. I feel stupid. Should have done this all along, I'm wondering if the trim guage needs to be calibrated somehow.

Trim gauges are notoriously variable between motors and boats. After all, we are relying, in most cases, on a little plastic lever that bumps against a cam to send the data to the gauge. It is always best to trust the "feel" of the boat and the data that shows you hitting max rpm at a particular trim angle, than to simply go off the gauge.

That said, to be honest, I am not all all surprised that you've found the optimum trim position for your boat/motor combination to be at almost 3/4 trim, as shown on the gauge. That would be fairly typical, I would think. My DF115's sweet spot Is very similar to yours in ideal conditions, except I am hitting about 6200rpm.

I still think you may be a touch under the ideal rev range. It would be better if you could get to 6000rpm at WOT when trimmed out like on your final test. You will get a bit better hole shot and possibly a bit better mid range economy too.

Lots of guys here in Aus like to run 4 blade props with their 4 strokes. More stern lift, mid-range economy and ability to hold plane in rough conditions offshore is the main reason, I think.

That, plus very few people here would even contemplate running at WOT for an hour out to their fishing grounds! Fuel costs here kill that sort of gas-burning behaviour very quickly! Most of us run our boats at cruise revs around 4200rpm for this reason.

Myself, I have stayed with the genuine Suzuki 3 blade SS prop that my excellent dealer recommended and supplied when I got the boat. Performs nicely for me. We did lift the engine 1 hole higher after about 100 hrs and the boat's handling improved just nicely, but we didn't gain anything noticeable fuel economy or revs wise.

If you are still contemplating a 4 blade, talk to Ken at Propgods and give him the data you outlines above about how the boat performs now. He will be able to recommend a 4 blader that will get you a couple hundred more rpm and do the job at the midrange, if that is your objective.