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| Playing with Inline Six Mercury Props http://ww.w.hpbc.ca/viewtopic.php?f=19&t=4642 |
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| Author: | Hounddog [ October 16th, 2024, 10:30 am ] |
| Post subject: | Playing with Inline Six Mercury Props |
I found this old video very interesting because back in the early 70’s I messed around with many different models of checkmate boats and many of the original small ear mercury chopper props. I would help new checkmate boat owners with the boat setup. We weren’t using setbacks back then, but dealers would have the motors mounted as high as possible on the transom. This young man like the majority of people back then doesn’t have “V Hull Driving Talent”. That’s the ability to fly the boat and get the most out of it. You have to be able to get past the chine walking stage and get comfortable with the boat running on the edge of being out of control. Funny thing with these chopper props. I never tested a good 28 pitch. The 26 pitch was OK but a bit lazy in getting up to 7000 rpm. Just about very 24 pitch was very good. There were 22, 20 and even 18 pitch. You could run them on the smaller horsepower motors. Today you can change the spline so the prop will fit triples and V4 motors. They usually are reasonably priced and work very well. https://www.youtube.com/watch?v=t9VTR5lHJM0 |
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| Author: | Hounddog [ October 16th, 2024, 11:03 am ] |
| Post subject: | Re: Playing with Inline Six Mercury Props |
Funny thinking back to that time. There were two checkmate hulls that I found challenging to drive. The first 1970 15 footer.....that’s the model prior to the MX 15...it had the rounded rear deck and very small pad. With a short shaft 6 cylinder the boat wouldn’t hang consistently and the nose would drop and want to hook. The other was the MX 13 with a short shaft 80 mercury. The boat would run great then do two big hops and blow over backwards. I had the large checkmate trim tabs on my boat and it happened 3 times. Performance props changed for the better from the 60’s thru the 70’s. The first inline 6 mercury props we got we the large thru hub elephant ear two blades. They had a lot of cavitation when you were getting on plane. We racers learned a very expensive trick with those props. If you thinned out the top inch of the prop blade it would bend and improve the performance. The problem was the blades would crack and couldn’t be repaired so you needed a new prop. The next version was the over the hub stainless two blade props. They worked better and you could do more personal modifications to them to improve the performance. The 3 blade chopper style followed. They were much better. But the problem for Canadians was getting them. Initially the supply of both the two blade stainless and 3 blade stainless props was only available in the USA and we didn’t get access to them for several months. If you were fortunate enough to run a BP mercury with the shiftable speedmaster lower unit. It was much easier to drive because of the gearcase and smaller diameter props. |
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