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 Post subject: Re: TI outboard mount
PostPosted: Fri Dec 08, 2017 4:15 pm 
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Location: Central Coast NSW Australia
Thanks for the link Nap and nice work with your unique outboard mount MC! 8)
Hope your testing goes well. I’m interested to see how well the rear cargo area drains with the mounts in the scuppers.
Do you have the reinforced scuppers?


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 Post subject: Re: TI outboard mount
PostPosted: Sat Dec 09, 2017 5:13 am 
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Location: Niceville, Florida
It’s kind of funny Nap, I would NEVER use a scupper mounted cart to transport a tandem island on land, but it seemed like the toughest part of the hull to do what I wanted with the motor. I was in the garage last night stepping on the prop, and mount flexes just enough, you can see the Delrin posts “shoving” the hull just perfectly. As far as holding water goes, it’s not a tight fit, and the motor is as far aft as practicable, hopefully to avoid the “firehosing” effect on the rear hatch! The boat is a late 2017, so I would think that it has the reinforced scupper holes. It is absolutely freezing here this weekend (don’t work on anything plastic), so a water trial is NOT likely, and thanks for the comments.

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 Post subject: Re: TI outboard mount
PostPosted: Sat Dec 09, 2017 3:25 pm 
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A ‘17 would have reinforced scuppers ...but I’m not sure if the rear scuppers were ever reinforced? Look for the black plastic tube inserts.


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 Post subject: Re: TI outboard mount
PostPosted: Mon Dec 11, 2017 3:53 pm 
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I need advice with two dimensions, distance from gunwale to top of transom (6” is not enough), and ball park distance from centerline of boat to centerline of engine, I used 13.5 and I have annoying cavitation, prop starts to slip at about 5.5 miles per hour. Engine is Honda 2.3 short shaft and the boat is 2017 T.I.
I hate to guess, its a lot of work to remake the transom, anyone experienced with this setup could help me avoid a bunch of experimentation. Thanks in advance.

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 Post subject: Re: TI outboard mount
PostPosted: Mon Dec 11, 2017 11:26 pm 
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Location: Central Coast NSW Australia
MC,
These specs apply to the Suzuki DF2.5 short shaft. I copied them from my post back on P11 of this thread.

The motor sits on a thin poly board 16.5 cm tall x 15cm wide attached to the alloy tube sections.

Poly board height above gunwale = 22.5cm
Centre of poly board to gunwale edge = 15cm.
It is important that the cantilevered section of the bracket sits above the gunwale to avoid getting hit by waves. Mine sits 5cm above the gunwale.
This pic might help:
Image


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 Post subject: Re: TI outboard mount
PostPosted: Tue Dec 12, 2017 7:02 am 
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Location: Colorado
Quote:
distance from gunwale to top of transom (6” is not enough), and ball park distance from centerline of boat to centerline of engine, I used 13.5 and I have annoying cavitation, prop starts to slip at about 5.5 miles per hour.


New problem I havent heard of.. You would need orders of magnitude more power than what you have to actually "cavitate" the prop and that would show up as some sort of vibration.

If the prop all of a sudden over revs, that would be ventilation and that is from air getting sucked down to the prop. If you are getting air sucked down to the prop, Im not sure what you had in mind but seems you would want to lower the prop in the water. Also, I cant remember from the video but did you have the prop shaft set at an angle? Cant say if this is good or bad but I dont think anyone has issues with ventilation (air getting sucked down to the prop causing it to over rev) with the shaft straight up and down..

???


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 Post subject: Re: TI outboard mount
PostPosted: Tue Dec 12, 2017 10:02 am 
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Joined: Sun Apr 20, 2008 6:18 am
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Location: Sarasota,Key West FL
On our 2010, 2011, and 2012 TI's, we used the same motor mount, just transferred the same mount to each new boat as we bought them, I'm assuming all the dimensions back there are the same even on current boats.
Our motor mount is 1.5" pvc and slides into the rod holders, (about 2-3lbs). The distance from the gunwale to the top of the 2x4 transom board is about 5-6 inches. Note the rod holders can only be used as placement holders, as they are not supported down below, (just look inside the hull to see what I'm talking about). I used spectra line for all mechanical support, (a truss similar to how small airplane engines are held in).
I mounted my engines ( twin Honda 2.3hp short shafts) as close to the hull as possible and tilted the engines inward at the bottom about 5 degrees so the props are under the hull. I get no cavitation when tacking even when one ama is way up in the air. We've been running this same setup with no cavitation issues for over 7 yrs now.

My only complaint about the Honda's is the centrifugal clutches, when you first start up the motors when cold they idle fine and the props don't spin, however once the motors warm up a little the idle speed goes up and the props partially engage. With my super high pitch props with the warmed up motors at minimum throttle (all the way down), with no sails or anything out, (basically during the time I'm pulling out of harbor) I can't get the boat to travel any slower than 5-6 mph, (at idle). As soon as I clear the shore and the harbor I increase the throttle enough so the clutches are firmy engaged, (about 1/8 throttle, I don't want to wreck my clutches), unfortunately this propels the boat up to about 7mph, which is a little fast for no wake zones. I sometimes have to kill one engine when going under bridges and thru canals. Once out in open water I increase the throttles slightly until the boat is going 8mph (a little below 1/4 throttle), I lock the throttles then pull up all my sails and sail to the best of my ability. The engines are still very quiet and we have no problems talking over the engine noise. You know the sails are pulling their fair share of the load when the rpm on the motors increase, (relieving the motors from their propulsion overhead, (ie.. crank shaft, gears, prop, and friction uses near half of available engine hp ). Typically twin engines help each other out with the mechanical overhead.

I have no desire to be anywhere near those motors so I always solo in the front seat, and have the throttles and everything extended up to the front seat so I never have to go back there. I hate the motor noise so I never run the engines any higher, (except in dire emergency of course, then I'm in get out of dodge mode (storms), then all bets are off). It only takes around 1hp to propel the boat to 6 mph, ( as proven out with mirage drives and two strong peddlers (around 1/2 hp ea), or with the Torqeedo 403's and Evolves ( both 1 hp equivilent), both propel a TI to 6mph at WOT, however both human power and electrics are only useful for very short distances at those speeds, (both well below my minimum acceptable cruise speeds). I flat refuse to go 2-3mph, (just sayin). All these popular outboards are designed to propel a 1200 to 1500 lb industry standard bass boat to 5-6mph, so all the props are wrong for these lighweight 200 lb boats, (my opinion). Also you have great risk of exploding the engines with the wrong prop pitch. My max speed , (15mph), requires a minimum of a 7 inch prop pitch, the stock honda has a prop pitch of 4.5", if you exceed 10 mph or so you have a big risk of blowing the motors up on a sailboat, ( yep I've blown up several). Keep in mind the motors only supply a small portion of your hp requirements on a sailboat.

With the low throttle settings I typically get around 3hrs runtime per tank(s) of fuel, ( the factory tanks are 1 liter ea), I don't recall the last time I had to stop and refuel while out on the water, (most of our outings are under 30 miles and under 3hrs of running).
With the motors tilted under the hull we had no difficuly steering, even when we had a big jib and/or spinnaker flying.
The entire setup ended up being an udder failure for me. My stated design goal was a human powered, (tri-powered) craft with a 12-14mph average cruise speed in any conditions with 150mpg fuel economy and a 300 mile in under 24 hr nonstop range. Never got even remotely close, the best I got to was 10-11 mph average cruise speed with a 200 mile range at around 80-100 mpg. So the entire design was abandoned. Sold the boat, but some of the ideas and solutions are hopefully useful to others.
I'm not suggesting anyone do anything one way or another, I'm just sharing what worked out well for us.
Hope this helps
FE


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 Post subject: Re: TI outboard mount
PostPosted: Tue Dec 12, 2017 10:43 am 
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Joined: Thu Jun 01, 2006 1:16 pm
Posts: 566
Location: Colorado
Quote:
yep I've blown up several)


What specific outboard motor did you blow up? Do you happen to know the brand and hp?


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 Post subject: Re: TI outboard mount
PostPosted: Tue Dec 12, 2017 3:20 pm 
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Joined: Mon Dec 29, 2008 2:35 pm
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Location: Niceville, Florida
OK Stringy, I have a lot of faith in your numbers, your videos look great. Today I cut some new pieces, everything is clamped together ready for drilling, thanks for your help. Unfortunately I can’t figure out how to attach a picture.

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 Post subject: Re: TI outboard mount
PostPosted: Tue Dec 12, 2017 6:46 pm 
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Location: Central Coast NSW Australia
mcoop57 wrote:
OK Stringy, I have a lot of faith in your numbers, ....

No pressure then! :wink:
Actually MC I’m confident in the height above the gunwale as that was the end result of a lot of experimenting. The distance out could probably be reduced but I ended up leaving it as the main sheet could get caught with the OB in the raised position. Better to have too much than not enough eh! :D
Hopefully the Honda short shaft specs are similar to the Suzuki’s?
Pics need to be hosted on an external site and then copy and paste the img code over. I use Dropbox.


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 Post subject: Re: TI outboard mount
PostPosted: Thu Dec 14, 2017 8:16 am 
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FE, Ive asked for details on the outboards you have blown up three times now, never a response. So.. I will assume that means that you nave never actually damaged a stock Honda 2.3 from over reving and Im sure you have never damaged a Suzuki 2.5 (you have never owned one plus they rev limit) or any of the other larger outboards that actually get used on TI's.

If you want to do a good and accurate job messing with the prop, you really need to measure RPM for how you you are using the outboard. Otherwise, you dont know if you even have a problem or if you did have a problem, are you fixing it or making it worse. You can actually make things worse than the manufacture intended by increasing the torque the outboard needs to operate at to achieve some hp. These outboards get used on canoes which achieve about the same speed a TI does and manufactures dont like to deal with warranty issues from blown up outboards. I posted this on another thread for measuring RPM but here it is again in this thread:
---------------------------------------------------------
I may get around to this some day but it would be interesting to get RPM readings with a review of one of these outboards.

If I were going to purchase a tach now, it would probably be this one https://www.amazon.com/dp/B01FZ3YMOQ/re ... B01E16UYFE

I have not tried this one but what I like about it is that the pickup sensor includes a wire your wrap around the spark plug wire PLUS a ground wire. Some of those dont have a ground wire and I think having the ground would improve the signal to noise - more reliable readings.

The Suziki 2.5 is about perfect for the TI. Prop is matched well and it has a ref limiter plus four stroke. But.. you have to deal with changing the water impeller periodically and also never start the outboard without the impeller actually pumping water. Nice power for the weight.

Someone should also measure the RPM for the Honda 2.3. As far as I can tell (from this forum), no one has ever damaged this outboard from over reving with the stock prop but I understand that someone has damaged those really small two strokes. Sure would be useful to actually measure RPM as some have messed with the prop without actually knowing if they had a problem that needed to be solved.

The Honda is of course a great little outboard but about three weeks ago I was standing next to a sailboat with the 5 hp Suziki four stroke. About 100 foot away, there was another small sailboat that had the Honda 2.3 four stroke. Both were idling and we noticed that the Honda was louder even though we were standing right next to the Suziki. This was not the 2.5 Suziki but I would guess its similar to the 5 HP Suzuki (both water cooled).

But.. that centrifugal clutch and never having to worry about the water impeller even running the outboard on the hard sure would be nice.

FYI, here is a video of that tach in the link above.. Its in Russion.. LOL.. but close enough..

https://www.youtube.com/watch?time_cont ... GiovbL9JjE


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 Post subject: Re: TI outboard mount
PostPosted: Thu Dec 14, 2017 12:51 pm 
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I got a chance to rework the mount today, posted a new video on YouTube. Thanks Stringy for the dimensions, probably won’t get a sea trial until after the holiday. Channel is “mcoop571”.

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 Post subject: Re: TI outboard mount
PostPosted: Thu Dec 14, 2017 8:51 pm 
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Joined: Thu Aug 16, 2007 2:25 pm
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Location: Central Coast NSW Australia
That mount looks great MC! 8) I took some screen shots from your video
Image

The Honda looks to be sitting in a similar spot to my Suzuki. When it’s sitting on the mount I get the following
distances from top of the polyboard mount to:
anti cavitation plate = 44cm
Propellor centre = 55cm

Just one word of caution, I see you are using the screw in cleats as part of your bracing.
Image

You are putting a lot of faith in those cleats and I hope they are strong enough. I know they aren’t solely used for bracing as you have the other mount sections that go into the scuppers but I’ve had problems on a few Hobie hulls with the plastic being paper thin in the molding.
Thoroughly check by screwing the cleat out and inspect the thread quality, plastic cup thickness and look for any perforations.


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 Post subject: Re: TI outboard mount
PostPosted: Fri Dec 15, 2017 11:00 am 
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Location: Sarasota,Key West FL
Walt:
Related to my TI's over the last 7yrs I have lost 3motors.
#1 was an Island hopper 2hp four stroke, (a mitsubishi motor). On the day the motor let loose the winds were around 22mph, I had all the sails out on a downwind run, the sails were the main, (90sq ft), jib, (40 sq ft), and my old big spinnaker, (130 sq ft), in those conditions the boat would typically top out right around 20mph. This was all back in 2011 time frame. I was out testing a new prop design to see what I could get out of the motor. I purchased that motor for the TI in april 2010, ( in those days I was only running single engines). The motor let loose right around 16mph (over rpm) and was destroyed. The motor was not stock, I had ported and polished it, and shaved the head. I was running a big bore carb that was over jetted. The motor was running 100 octane leaded aviation fuel and 36% nitrox with a very slight over pressure, (maybe a couple psi over boost). A wild guess at the motor hp would be maybe 5-6 hp, however keeping that motor cool was an issue. Island hopper #2 was kept pretty stock with the stock carb but was re-jetted, re-propped, and I only ran 36% nitrox thru it a couple times, (just playin around), it lasted thru 2012 but was always very lame, (I hated those motors). Island hopper #2 never exploded, ( it was retired) so that one doesn't count.

#2 was a Honda 2.3 four stroke purchased in early 2013. I resisted tricking it all out, the only mods to that motor was a little re-jetting (stock carb), I just used premium gas (93 octane), but did have a propane bottle ( to richen the fuel mixture) and a 36# nitrox port drilled into the air intake, ( just playin around), everything else remained stock. I never over boosted (super charged ( over pressure)) that motor. I was out testing a new prop design, (similar to #1 conditions). The motor threw a rod and was destroyed at right around 18 mph, (over rpm).

After the #1 Honda debockle I replaced the single engine with twin matched stock Honda 2.3's, I kept the motors pretty stock, (well stock for me anyway, I did add the Nitrox port, nothin else fancy though, (can't help myself lol, I'm a motorhead)).

#3 (Honda 2.3) was not destroyed from over rpm. In 2013, (might have been early 2014, don't remember for sure) I was out a couple miles off siesta key beach just playing around, I had the hydrofoils on the boat and was testing out my new 10" pitch custom props, winds were a little over 20, I was foiling downwind, running right around 20mph when the boat hit a big wad of shark fishing line (dieema, probably 100 lbs test or better), about 200 ft long. I was running 36% oxygen enriched nitrox into the stock motors at the time, (26%-28% oxygen at the very most, vs the normal 21% in normal air), no re-jetting or propane. The motors were of course at WOT running at max rpm, (I'm guessing around 6000 rpm (20 mph is max speed with these motors with the ten inch props).
The fishing line wrapped around the right foil, the front mirage drive, the rudder, and the right prop. When the line wrapped around the prop it tore the right foil off the boat ( destroyed), bent the miage drive up and snapped the rudder off (rudder pin). The entire lower unit was ripped off the motor, and the crank got bent. The boat pitch poled and dove, goung from 20 to zero in one second flat, the boat was heavily damaged, and one of the foresail masts snapped in half, and destroyed the sail, then to add to my humiliation I ran over the sail, (again, I had done that before in other accidents and pitchpoles). It took quite a while to struggle the crippled boat back in. The foils were retired that day (just too dang dangerous).
The replacement motor remained totally stock, and I re-focussed most of my efforts since then on increasing efficiency and fuel economy with my wing sail tech and custom props, leaving the engines pretty much stock. Haven't really made any major changes to the boat over the last three years, just using it as is. Never did make the wing main sail, designed it a few years ago, and even bought the materials, but never got the ambition to build it.

Epilog:

My original stated design goal, (stated I think on this forum, back in early 2011) was to build a human powered craft, ( utilizing the tri-power capability of the craft that Hobie invented) that would average 12-14mph cruise speed in very light winds (3-7mph natural wind, independent of actual wind direction, including near directly up wind). With the hybrid supplimental propulsion I needed 150mpg, and the ability to go 300 miles non stop in under 24 hrs, regardless of conditions). Basically I'm old, crippled and an insulin dependent diabetic. I'm not athletic by any stretch of the imagination and my only chance of completing the 300 mile everglades challenge race would be to cheat by any means possible and design a boat revolving around my limited capabilities making it possible to complete the race in class 6 experimental class in 24 hrs or less, (nonstop). Once the battery/solar/ electrics catch up the hybrid gas propulsion systems will be switched out with solar,battery, fuel cell, servo electric tech for the supplemental propulsion. Basically the plan was for twin torqeedo 403's (re-propped). With solar panels on both tramps during day time operation, then a fuel cell based charging system for night time operation, (the fuel cell is my own design, and has been ready and waiting for the rest of the tech to catch up). The biggest challenge was inventing and developing the correct wing sail technology, that was solved a couple yrs ago, ( pretty much the key to everything).
The entire program was a dismal failure, I never got even remotely close to my design goals. The current design can only cruise at around 10mph, (upwind in 3-7 mph winds), fuel economy averages around 80mpg, ( averaged out over the last 3yrs), and nonstop range is only 200 miles. I know my own physical limitations and am pretty sure I can pedal the eclipse flow 90 mirage drive at 40cpm, (walking pace) up to 24 hrs, (obviously with a few breaks), I've done quite a few 60-80 mile day runs preparing and testing. The flow 90 fins have been tested quite a bit and provide useful propulsion up to around 12mph, (regular turbo fins are only useful up to around 8mph). Of course the boat was heavily hardened and offshore capable with all it's massive sail sets , spinnakers, jibs, main, etc) and normal sailing capabilities, and can handle most conditions within reason.

Unfortunately my health has deteriorated and have been ordered by my docs to give up sailing, ( lol, I'll take up basket weaving I guess). The boat was dismantled and sold last month, I had to retire ( health reasons),and all the gadgets were cut up and put out to the road.
I have hopes if my health improves next summer, it wouldn't take much to pick up a new TI (would be my forth), all the gadgets are all incredibly simple and would only take a couple weeks and a couple hundred bucks (material costs) to re-make if I get the ambition. Besides 90% of the gadgets were over 7 yrs old and looked like they had survived WW2.
I'm hoping someone else picks up the ball and can get a modified TI thru the EC in under 24 hrs, (it can be done).
Lol I'll be watchin.
FE
Edit: I think you may need to have special licenses and certifications to buy leaded avgas (pilots license) and nitrox up to 36% (nitrox gas diving certification). Obviously running oxygen enrichment (NOS is 36% oxygen, and really expensive) and exotic fuels (nitro, etc) can get quite dangerous, ( just saying).

Don't blame me for all this stuff, Hobie is the one who invented all this tri-power stuff back in early Feb 2010.

Here is the video to prove it.
The reason I bought my TI in April 2010 was because of this video, (worst and most boring video of all time, lol)
https://www.youtube.com/watch?v=241QmxFcbuc



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 Post subject: Re: TI outboard mount
PostPosted: Fri Dec 15, 2017 4:26 pm 
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Joined: Mon Dec 29, 2008 2:35 pm
Posts: 59
Location: Niceville, Florida
Mr FE, did you “yard sale” the modified props for the outboards?

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