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
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4 Blade Propco Slingshot Prop For My DF225?
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Originally posted by Sunstate78 View PostSo 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.
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.Last edited by Moonlighter; 05-06-2015, 09:50 PM.
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