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PostPosted: Mon Aug 05, 2013 6:46 am 
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Fuz
mine is the 2.3 Honda.

Here is the idea for the modified bracket. I suspect that using the yakattack rails I could position it is different places with alternative tabs (yellow) for the different points on the hull.

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PostPosted: Mon Aug 05, 2013 7:08 am 
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Chopcat :
The design looks strong enough to me, even with aluminum sq tubing it would likely work ok with your added diagonal brace. I'm still concerned though that you might have the motor mounted way too far forward, the middle of the motor will be next to you when sitting in the back so you might not be able to reach the control easily without leaning forward when in the back seat (plus pulling the starter will be a (censored)), and it's still too far back to reach from the front. And might be more in the way where you have it now.
Also make sure you can tilt that motor so the prop is out of the water, and the front isn't in the water when tilted, when I was checking out outboards, that would have been the case with the mercury outboard on my boat, I would of had to design a swing down motor mount to use the Merc (never measured up the Honda though)

I don't know if you can lock the tiller and throttle on the Honda like I can on the Island hopper. Basically I start the motor, lock the throttle and tiller then climb back up to the front seat to drive, the down side is if something were to happen I would have to climb back there quickly to kill the motor (what I have now is probably not safe).
I used pressure treated wood for my motor mount board, the original pine board only lasted a few months and had to be replaced (rotted in salt water).
Hope this helps
Bob


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PostPosted: Mon Aug 05, 2013 8:39 am 
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I think your design is similar enough to this UltraLight mount that works fine to rule out problems with torque.


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fusioneng wrote:
I'm still concerned though that you might have the motor mounted way too far forward, the middle of the motor will be next to you when sitting in the back so you might not be able to reach the control easily without leaning forward when in the back seat (plus pulling the starter will be a (censored)), and it's still too far back to reach from the front.

I agree. With my latest mount that is back at the rod holders my motor is still too close for comfort. It is acceptable to me for the limited amount of usage it gets, but would be totally unacceptable for full time use. Having it mounted further outboard would help in the comfort factor also, but the further you go out the higher it would have to be to keep from digging in the water when under sail leaning to that side.


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PostPosted: Mon Aug 05, 2013 10:55 am 
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Chopcat :
Here is a pic of my Island hopper motor.

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The mote marine bag covering the motor (Mote marine research is a marine wildlife organization here in Florida) is to fool the motor haters into thinking I'm green ( LOL)).

You can see the centerline of the motor is way back at the rod holders (quite a ways back from your position), when sitting in the rear seat the tiller position is just about right. My only regret (besides the motor really being a fresh water only motor, and not powerful enough, etc) is the motor is on the wrong side of the boat for me, and it's a real pain for me to pull the starter rope.
You can see from the pic that when my motor is tilted forward it is almost sitting on my lap when sitting in the back seat.

I really like the first pic Hildabrew has above, You could still use your rack mount system, and square tubing all around, but would just have the motor at the back of the brace instead of the front. Notice they also has a simple pin to remove the motor, that's an excellent idea.

If you have problems with getting the motor out of the water when it swings up, that front joint could easily be converted to a swivel joint so when the motor tilts it pivots on that front joint (only if needed, as I would have had to do on the Merc motor).

His second pic would also work but I think I would add a brace that touches the hull rail (like in your design) just to obsorb some of that rotational torque, which is a big problem on my smaller 2hp gas motor. Keep in mind a Torqueedo is fairly equal to a 1hp motor (30 lbs torque, where your Honda 2.3 will have much greater torque).

If you look inside your hull at the scupper hole supports (there aren't any), on one of my TI's I back filled around the scupper supports with urethane foam, it helped but what a mess that foam makes.

Another annoying problem I have is when I'm power sailing and on the tack where the AMA on the same side of the motor is up in the air, the prop sucks a lot of air and cavitates badly, so make sure your prop is plenty deep. I can't get my motor any lower so I'm kind of stuck with that problem. I just measured and the centerline of my prop is 16 inches below the rail of the boat (measured just behind the rod holder).
You can hear the prop sucking air in this video at around 4:10:


Another thing I did was went to a 7 inch pitch prop, the standard 4 1/2 inch pitch prop that came with my Island hopper motor was for much heavier boats, and my top speed was only about 4mph.

Hey if you get all the details works out I might invest in a Honda sooner than I had planned. From everything I have read, the Honda's are the best out there (I kind of regret buying that Island Hopper, but it's reliable, and is over 3 yrs old now, and keeps working.)


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PostPosted: Mon Aug 05, 2013 2:25 pm 
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i will have to have a think about the position. Tiller length will have a lot to do with it.

The honda has a tiller handle that is 250mm / 8" forward of the mount bracket so i was thinking i would be sitting there with my arm forwards onto the tiler. This is where nudling has it. The motor in his photo is the Honda and mounted in a similar position to where I was proposing.

I shall have a mock up again and check

CC

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PostPosted: Mon Aug 05, 2013 4:34 pm 
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Chopcat :
That's all I was doing was observing based on where mine and others are mounted, and seem to work well (although on different brands of motors), and just suggesting you maybe mock up and double check that the motor position you are suggesting and confirm for yourself it will be ok for you, that's all.

I have an interest here because I'm thinking about changing to a Honda motor myself, and will need to go through all the same stuff when I do make the change, (knowing my current mount will not work on a Honda), plus all my stuff is nearly worn out after 3 yrs of heavy use.

Bob


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PostPosted: Tue Aug 06, 2013 7:27 am 
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i feel an adjustable model is now in the concept stages!

CC

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PostPosted: Wed Aug 07, 2013 9:06 am 
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Here is the adjustable virtual version

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CC

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PostPosted: Wed Aug 07, 2013 1:47 pm 
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Chopcat:
Cool design, you could slide it forward to drive from the front seat, or slide it back to stear from the back. Then when not using it you can slide it all the way back to get it out of the way. At least on my TI getting the weight as far back as possible helps a lot.
I called the dealer today and priced out the Honda 2.3 motor, they said it will take about a week to get the motor in.
The only remaining thing to determine for me is if I should get the 15" inch shaft or the 20" , still have to figure that out.
It will be interesting to know how fast you can go with the 2.3 in calm conditions, my island hopper max's out around 6-7 mph in calm water. With the 7 inch pitch prop the motor can't get to full rpm (not enough hp), I read in the Honda specs that the prop pitch is 7 inches, so it should be able to propel a TI to 10 mph (in theory anyway)
Good luck
Bob


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PostPosted: Wed Aug 07, 2013 2:27 pm 
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fusioneng wrote:
It will be interesting to know how fast you can go with the 2.3 in calm conditions, my island hopper max's out around 6-7 mph in calm water.

I'm really interested in that as well.

I can hit around 7.5 MPH with my Torqeedo Travel T1003 and it has 68# thrust. I read that the Honda 2.3 only has 66# thrust. I can't find any info on TI's with gas outboards but have found two YouTube videos of AI's .. one with a Mercury 2.5 and one with a Honda 2.3. The Honda states "6.5-7 knots" max, the Mercury states "8-9 mph" max. That's about the same, but I thought someone here had posted that they were getting 8 MPH at half throttle, I don't remember who posted that or what engine that was.

I tried a higher pitched prop but didn't get any faster top end. I think it would probably extend the range at lower speeds due to the motor not spinning as fast. I stuck with the standard prop because it is two blade rather than three allowing it to lay flat (I can stow the T1003 under the front hatch - my usual launch point doesn't allow motorized craft so this way I can have still have the motor onboard for emergencies).

IMO the TI will go 5 MPH easily - each MPH over 5 gets exponentially more difficult.


Edit: Here are the videos if anyone is interested (speeds are in the comments):

Honda: http://www.youtube.com/watch?v=oTW40ugkPZ4

Mercury: http://www.youtube.com/watch?v=5xUm26niyR0


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PostPosted: Wed Aug 07, 2013 3:54 pm 
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My little Suzuki took me 8mph at half throttle. I'm still breaking the motor in, so that was as far as I could go. At that speed though the rear hatch was basically underwater in spray. I raised the motor another 6". But have yet to test it out. Just returned from Bali, now up in Tahoe, then back home and will finally post my pics!


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PostPosted: Thu Aug 08, 2013 9:52 am 
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The honda is my video btw. I top out at 8mph max which is a little surprising and disappointing when compared to a 2.5hp yammy. Rudy mentioned that his does 7-8 mph at 1/2 throttle -- same with Steve's suzuki. On the plus side, it's air cooled so you can run it on dry land if you need to cycle the fuel through and it doesn't need flushing.

As for shaft length, I would get the 20" instead of the 15" if I could do it again. The motor being mounted 6" above the AKA bar and the propeller is situated just beneath the yak for a short shaft.

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PostPosted: Thu Aug 08, 2013 10:33 am 
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Remember, the top speed of these boats without planing can be calculated by the length at the waterline. I get about 7mph for the AI and 8mph for the TI. To go faster than that without help from a current or waves requires many times more energy. So if you can get to 7mph on an AI at half throttle, you may only get to 8mph with full throttle. With the design of our boats the use the formula is not exact, but going much more than 7-8mph will take much more power than getting up to that speed.

I'm enjoying the discussion and look forward to the results and further designs.

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PostPosted: Fri Aug 09, 2013 1:01 pm 
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So we are not going to be water-skiing then?
CC

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PostPosted: Fri Aug 09, 2013 1:35 pm 
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Chop at:
Why not, we have a tow rope on our TI and when we have outings I tow the small kids around on boogie boards, they have a blast. I found out the hard way that the tow rope has to be a little longer and tied in the center otherwise you can't steer ( the rudder on the TI is a little smallish).
Also when out lobstering I tried towing two divers behind the boat, hanging on ropes, one behind each AMA ( about ten feet) well that didn't work out so well couldn't steer at all. But we had no problems at all towing our 4 person inflatable boat ( we call it the dingy) , as long as it was tied in the center and 20 ft or so behind us. We had all of our dive tanks and gear in the dingy (650 lb capacity).

Hey I took my boat up to Honda dealer and he looked the boat over, and I ordered a new 2.3 Honda short shaft. He thinks it will work fine on my old motor mounts, so it looks like it's going to be just bolt it on and go. The motor will be in early next week. I'll let you know how it goes. I'll probably hang on to the island hopper for a while ( just in case) it's been a great little motor for us over the last 3 yrs. I imagine used motors are hard to sell.
Bob


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