Dam banded, your kawi runs pretty good! Maybe share some tips with this guy ^^
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| Transom height experiment http://mudmotortalk.com/mmt_v2/viewtopic.php?f=2&t=67671 |
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| Author: | cupnglide [ Wed Jul 27, 2016 8:57 pm ] |
| Post subject: | Transom height experiment |
I enjoy trying to solve a good problem. The one I've been working on (for too long) is a slow boat. The boat / motor combo isn't that well suited. Gator Trax 1650 hybrid hunt deck (17'8" long) and a 2013 PD Gen3 EFI. The boat has the V bow and round chines. I had the transom at the height PD recommends. Problem was, the boat was slow out of the hole, plowed, ran wet, and usually averaged 20-21 mph. Moving weight around made those numbers drop. It seemed like the shaft/prop angle to get half in / half out on the prop was pretty steep (heavy boat runs deeper in the rear, right). So I had a welder friend drop the transom to 17.75" dead center. The motor went back on laterally in the exact same spot. This flattened out the angle a good bit. It put the handle in a better driving position. Deep water into the wind was 22.5. With the wind was 25. No wind, deep water was 24. No before and after video proof, but there's a witness to the before and after numbers. The hole shot getting on step is crazy. This, with the 2:1 gearing and a prop that could use some work, has me pleased with that $80 welding bill. YMMV. Just thought I'd share. |
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| Author: | Gigafowl [ Wed Jul 27, 2016 9:17 pm ] |
| Post subject: | Re: Transom height experiment |
Angle of attack change... Shims might help too.... Place a wedge between MM and transom with thicker end on bottom to also improve angle of attack for prop even more.... GTrax transom angle was designed and optimized for MB... |
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| Author: | BlueShamu [ Wed Jul 27, 2016 9:34 pm ] |
| Post subject: | Re: Transom height experiment |
Thanks for the update...this is something I have been contemplating for a LONG time! Glad to hear it worked out for you. Sent from my iPhone using Tapatalk |
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| Author: | cupnglide [ Wed Jul 27, 2016 9:43 pm ] |
| Post subject: | Re: Transom height experiment |
Appreciate the tip, Giga. That may be next. The results were encouraging enough to make me reconsider the 1.52:1 conversion. It has such a hole shot now, I think it would still get up quick enough with the 1.52. And I should gain a little more on top. |
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| Author: | Will C [ Wed Jul 27, 2016 9:48 pm ] |
| Post subject: | Re: Transom height experiment |
Nice when a test works that good! Mine is a 1744 gdsd short t. Raised my engine 1". On test run i could not find a sweet spot for trim and turned like poop. I put it back down and is all good. A littlle change can do alot, good or bad |
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| Author: | banded-mallard [ Thu Jul 28, 2016 4:19 am ] |
| Post subject: | Re: Transom height experiment |
PD recommends 19.5". I dropped mine to 18" simply so that the lower unit would spin "under" the hull rather than the cav plate hitting the transom. Now, I will tell you that when trimmed up, I do now have more tiller torque, but my stage 2 runs 33-34. One thing you need to keep in mind being you went a lot more. By dropping the engine, you have changed the outdrive angle, which is a plus. More "forward" thrust. But is the same token, your engine will appear that it is leaning forward a very dood bit. My buddy said he has noticed that mine looks like its over trimmed, but its not, the prop still grabs. If you drop the frame too much, and the engine is leaning forward too much, your oil level will not be the same and you could possibly do damage to block. It would be similar to running the engine on its side. Some engnes have a low oil shutdown switch. I cant remember if the Briggs has one or not, but keep that in mind when trimming up too far. |
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| Author: | cb5331 [ Thu Jul 28, 2016 7:08 am ] |
| Post subject: | Re: Transom height experiment |
It was an option on the briggs. Most don't have it. |
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| Author: | Will C [ Thu Jul 28, 2016 7:37 am ] |
| Post subject: | Re: Transom height experiment |
Dam banded, your kawi runs pretty good! Maybe share some tips with this guy ^^
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| Author: | JLACOUR [ Thu Jul 28, 2016 7:40 am ] |
| Post subject: | Re: Transom height experiment |
| Author: | banded-mallard [ Thu Jul 28, 2016 7:48 am ] |
| Post subject: | Re: Transom height experiment |
| Author: | cb5331 [ Thu Jul 28, 2016 8:25 am ] |
| Post subject: | Re: Transom height experiment |
| Author: | banded-mallard [ Thu Jul 28, 2016 8:38 am ] |
| Post subject: | Re: Transom height experiment |
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| Author: | Will C [ Thu Jul 28, 2016 10:10 am ] |
| Post subject: | Re: Transom height experiment |
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