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PostPosted: Thu Aug 24, 2017 9:34 pm 
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Location: Colorado
Curious if you happened to measure peak speed with and without the 10 degree angle change?

FYI, I think its the outboard shaft that kicks up wash, not thrust from the prop.. Could be wrong..


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PostPosted: Fri Aug 25, 2017 1:57 am 
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Location: Central Coast NSW Australia
I'm not sure of the benefit of a 10 degree transom angle?
Any change in trim angle could cause either hull plowing or porpoising. When I mounted the OB I wondered whether I would need to adjust the trim angle but found it unnecessary as the motor was at the right angle mounted directly to the gunwale with no plowing or porpoising.


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PostPosted: Fri Aug 25, 2017 4:10 am 
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walt wrote:
Curious if you happened to measure peak speed with and without the 10 degree angle change?

FYI, I think its the outboard shaft that kicks up wash, not thrust from the prop.. Could be wrong..

I'd like to see a speed test with both angles. When I repower my boat with the Suzuki I will test it.

On my boat I had both wash from the outboard shaft and from the prop thrust. Mounting an engine on the side of a boat is certainly not ideal but unfortunately necessary with the transomless TI.


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PostPosted: Fri Aug 25, 2017 4:18 am 
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stringy wrote:
I'm not sure of the benefit of a 10 degree transom angle?
Any change in trim angle could cause either hull plowing or porpoising. When I mounted the OB I wondered whether I would need to adjust the trim angle but found it unnecessary as the motor was at the right angle mounted directly to the gunwale with no plowing or porpoising.

The ideal trim angle can only be found via experimentation. Without a 10 degree wedge and the motor trimmed to it's lowest setting, it was trimmed at a slightly upward angle. This seemed to work well, the bow would plane a bit but not porpoise which is exactly what you want. The only downside was that a rooster tail from the prop thrust would wash over the back of the boat. This prop wash is normal and you can see it on any powerboat, it's no issue on transom mounted motors, but it is a bit undesirable for the side mount on the TI.


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PostPosted: Fri Aug 25, 2017 6:23 am 
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Location: Colorado
Using google pictures the firs time to post a picture. (which did not work.. edit to use face book - picture will go away after some time). I dont think I will mess with the angle.. but it would be interesting to see if it does change speed at all. The wash I get comes off the shaft fairly close to the water surface.

Image


Last edited by walt on Fri Aug 25, 2017 10:42 am, edited 1 time in total.

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PostPosted: Fri Aug 25, 2017 9:07 am 
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Walt,
I could not see your picture.


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PostPosted: Fri Aug 25, 2017 10:48 am 
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Location: Colorado
I tried another experiment.. put the picture on FB and set the privacy settings (on FB) so that only I can see the picture. However, I think you likely will be able to see it here in the edited post a couple back but it will also go away in a few weeks.


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PostPosted: Fri Aug 25, 2017 12:01 pm 
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Now I could see it Walt.
I am lost at what 10 degree angle. What angle? Where?


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PostPosted: Fri Aug 25, 2017 12:29 pm 
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Location: Colorado
The 10 degree reference is a few posts back. I believe it is a small angle change to the mount and it would result in the outboard thrust being vectored slightly down some and it would also result in the outboard prop being closer to the water when the outboard was rotated out of the water (hopefully still completely out of the water so you dont get any drag) Some boats have a transom that has some slope. My sailboat transom does not and is similar to what most of us have with the rear mounts that are flush. I get wash over the rear round access plate and some say those are water proof.. but mine is not and that wash results in water in the hull if you are motoring long enough. I once motored for about three hours and probably had 5 gallons of water in the hull. So I added a lexan shield to the motor mount that deflects the wash. After I put this on, I get very little water in the hull even after motoring long distances. In the attached picture (also hosted on FB so it will go away in a couple weeks), the guard is placed exactly where the wash is.

From looking at both pictures, thrust from the prop would need to shoot up at a like 60 degrees or something like that if it were causing the wash. Well.. I have a hard time thinking that is actually happening. The shaft moving through the water at 6 to 8 mph looks way more likely to me to be causing the wash. But.. I could be wrong. Could be something related to using the Honda instead of the Suzuki, could be that the more downward thrust lifts the back end a little and that helps reduce the wash with the tradeoff of maybe slightly lower top end speed. Since I have the lexan guard, its no longer a problem I need to solve.. but who knows.

Image


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PostPosted: Fri Aug 25, 2017 8:22 pm 
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I will not get back to my TI's location until next Tuesday. I will try to post a picture at that time. I am new to this forum so I will need to figure out how to post pictures from an iPhone. I will also do some speed test using the Honda as the sole source of power to determine what notched trim setting gives the best performance. I have read that the best trim angle for a planning hull boat is 4 to 5 degrees. Keep in mind that position of the center of gravity of your TI is based on your load distribution; therefore, my results may vary from yours. By mounting my Honda at a 10 degree transom angle I have the ability to adjust how high or low I want my bow out of the water at the load and cruise speed I chose for that day. If you have a zero degree transom you are limited on the amount of adjustment you have available.


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PostPosted: Sat Aug 26, 2017 12:16 am 
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CobraIP wrote:
so I will need to figure out how to post pictures from an iPhone. .


IMO the best way to post pictures is from iPhone actually..

Download Tapatalk which works very well... it's not so good (well I can't work it out very well :? ) for following conversations etc. but since you will probably take the picture with the iPhone anyway it's definitely the easiest that I've found. :D

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PostPosted: Sat Aug 26, 2017 1:26 am 
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Just got it. I will try to post a photo when I get it. Thanks


Sent from my iPad using Tapatalk


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PostPosted: Sat Aug 26, 2017 1:29 am 
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Now that Photobucket is no longer viable, I've found that imgur works best for posting photos to forums. Simply create an account there (free) and then upload your photos (best to use albums). From there you can then grab each photo's url for embedding into posts.

Try it, it takes a little getting used to the odd format, but once you master it you will have a stable location for posting your photos.


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PostPosted: Sat Aug 26, 2017 8:13 am 
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Location: Colorado
Quote:
TI is based on your load distribution


Yep.. and on the TI, a big variety of ways to load it. One person in the front or rear seat, two people heavier or lighter front to back. They get used all ways.


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PostPosted: Sun Aug 27, 2017 12:06 pm 
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My son took some photos of my outboard motor mount. I will try to post them. uploads.tapatalk-cdn.com/20170827/be34b4af663fad1ca20ce61cc63556a8.jpg[/IMG]ImageImage


Sent from my iPad using Tapatalk


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