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 Post subject: Largest outboard for TI?
PostPosted: Fri Nov 22, 2013 5:04 pm 
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What is the largest outboard anyone has tried or heard of for the TI? I am interested in putting one on mine for those long days after fishing when I am too tired too paddle/pedal 10 or more miles back home and there is no wind blowing. I have seen the videos of 2.3 to 2.5 outboards on the AI but was wondering if anyone has tried a 3.5 up to 6hp on a TI.


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PostPosted: Sat Nov 23, 2013 7:53 am 
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Location: Sarasota,Key West FL
jeffreydc:
I've had gas motors on my TI's for about 3 1/2 yrs now. I'm kind of a destination sailer, and we mostly use the boat for Island hopping, scuba diving, and basically our TI replaced our Sea Ray powerboat so pretty much everything we did with the sea ray we do the same with the TI. We have several powerboating friends that we typically meet out at some remote sand bar and just hang out once in a while (like tailgating), pretty much all the standard stuff. Our TI is our SUV and we often have 3-4 people on board (I've had as many as 6). When we have a large group or a lot of scuba equipment (6 or 8 tanks), we typically deploy our dingy which is a 4 person inflatable ( 650 lbs additional capacity that I store in the front hatch when not being used) and tow it behind the TI. Many times we also tow groups of kayaks when we have too many people. In the keys most of the coral reefs are 5-10 miles from launch, a typical day for us can be as far as 50 miles travel as we go from one place to another (obviously not 50 miles out into nothingness, that would be nuts).
I bought the first outboard because the first night out on our new TI back in spring 2010 my wife and I got caught in an outgoing tide (about 6mph) in one of the big passes into Sarasota bay trying to come in from offshore in late afternoon when the wind died completely (pretty stupid and dangerous thing to do, but we were 'who knew' LOL). Needless to say it took us about 2 hrs of really hard pedaling to get back in so I got a free ticket to buy a motor from wife.
(if your married and your wife is giving you issues about spending the money, just check the tides first and take her out in the late afternoon when you know the wind will quit, 'it works' LOL ). I'm just sayin I deny any knowledge of this.
If you go to the topic Ultimate Tandem Island ( viewtopic.php?f=69&t=33720&start=135 ) in the later pages you can see some of my escapades starting to use the motor for more than an emergency safety backup.
In south West Florida the typical winds are just not there 10 months out of the year (typically 4-6 mph (if that much)) and in the hot sun it's like sitting in a frying pan out on the water unless your moving at least 6-9 mph. In the low typical winds around here with a stock TI (with just a mainsail) you can pretty much expect to go 3-4 mph while pedaling, and literally fry out there in the sun.
If I were you I would look into the tri-power capabilities of your TI ( wind, pedal, and auxiliary power (hybrid gas or solar/electric). Here is a GPS track from a typical day for me in around 5mph winds using the tri-power capabilities of my TI.
Image

Wind direction simply doesn't matter since you are creating your own apparent wind to propel the boat. Actually the best performance is almost directly up wind because the wind coming at you increases the apparent wind going over your sails. And obviously downwind is the worst since i'm sailing faster than the wind I run over my huge spinnaker (135 sq ft) so it becomes useless unless the winds are faster than 15 mph or so, then it's like driving a rocket downwind.

Any more I only powersail, I can literally go out for the day and maintain speeds 6.5 to 10mph all day and it only costs me a buck or two in fuel. I always carry enough fuel on board (2.3 gallons) to go between 150 and 250 miles if needed (economy is dependent on how much wind of course).

Yea you could probably mount a Honda 5hp motor on your TI, but keep in mind the TI has a displacement hull and peaks out at around 10mph, and the horsepower requirement goes up exponentially. If you go to this web site you can calculate your boatspeed from the prop ( http://propellerhub.com/boat-speed-calculator.html) (the Honda 5hp has a 7" pitch prop and tops out around 5500 rpm). However because the TI has a displacement hull (can't plane) you will never see the 15 mph on a TI, it would require more than 50 hp to push the TI over 15 mph according to my calculations.
If you plug 500 lbs, 5hp, and hull factor 100 into this calculator it comes out to about 10mph ( http://continuouswave.com/cgi-bin/crouchcalc.pl ), about what you can expect as your top speed with a Honda 5hp motor with propeller drive only (not using sails or pedals at all). I'm a former powerboat racer myself, and have designed and built several boats over the years. We still have friends that we hang out with who race in the superboat races in both Sarasota, and Key West annual superboat races (we have houses in both Sarasota and Key West).
If you don't believe me about hull speed and horsepower requirements you can go to this web site and calculate it all your self ( http://www.psychosnail.com/boatspeedcalculator.aspx). The math is just not there (that's why jetski's have 120 hp). Of course there is some planing going on even with a TI at higher speed especially if you can get the bow out of the water. I've had my TI up to 18-20 mph of a few occasions (in strong 22mph plus downwind runs (with all 265 sq ft of sail up), but have also had the rudder snap off and AMA's break at those speeds so it's not safe, and hitting a large wake at that speed would destroy the boat (the front hull would fold in the area around the front hatch without proper re-enforcement), and any side gust that would bury your AMA would instead snap them off (I'm talking about the bars themselves, not the little nylon pin).

I Highly recommend the 27 lb Honda 2.3 hp outboard, it is extremely well built, reliable, and lightweight and will give you years of trouble free service. If you use it in conjunction with your sails (tri-power sailing) you can go out all day for just pennies in fuel regardless of the wind direction and speed.
Good luck
Bob

EDIT:
A word of caution if you have the motor in the water and running (with clutch engaged) at higher speeds (over 12 mph) there is a great risk of over revving the engine and it will explode, so if going fast you must raise the motor. FYI


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PostPosted: Sat Nov 23, 2013 9:08 am 
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I have a Mercury Marine Verado Four-cylinder 200 mounted on my TI. It has a dry weight of 510 pounds. I admit that the boat is a bit unbalanced, and I've only been able to get it up to about 35mph. But it's been an exciting project.


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PostPosted: Sat Nov 23, 2013 9:22 am 
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Location: South Florida
Wow! Are we talking "powerboat lust?"

Keith

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I sail: Biscayne Bay, Everglades to Cape Romano, Ft Desoto, Cedar Key

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein


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PostPosted: Sat Nov 23, 2013 9:35 am 
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Nah... It just seems natural to me. I admit, getting the mounting right was difficult, and the 510lbs hanging off the stern lifts the bow about 2 feet outta the water. But it kinda changes the hull from displacement to semi-planing.

I've had a few super close calls at top speed (35mph), and I lost the tip of my little finger when I capsized at speed due to "torque" ster. But all in all I think it's been a huge improvement to the existing stock TI. I'm hoping that Hobie will consider it as a dealt option.


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PostPosted: Sat Nov 23, 2013 9:37 am 
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Oh, one of the most difficult mods I had to make, was to use the amas as gas tanks. I had to blowin a liner and then route fuel line all the way to the stern. (They only leak a little bit, but the lake I live on isn't that clean anyway).


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PostPosted: Sat Nov 23, 2013 10:56 am 
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Location: Sarasota,Key West FL
Kieth:
Using probably too many words, I was trying to show jeffreydc a way to figure out for himself that adding a big motor to a TI is a big waste of time and money, and if he is unhappy with his performance and wants to add a safety factor (emergency motor) like I did, and/or get better performance in light winds there are ways to make it all work to your advantage. That's all

leelanauX: if you run nitro fuel in your engine be careful the fuel may melt your AMA's, plus make sure you run your tuned exhaust way behind the boat because the nitro fumes burn your eyes really bad. Try adding foils, with a 20" pitch prop I see no reason you can't get 100mph plus out of your TI. You will need one foil on each AMA, then one in back (like a three point hydroplane). I can calculate the foil design and size requirements if you need me to. Hey if you pump that Verado up to 1000hp I'm not sure the lower unit is up to the task. Also when taking off I would have to climb way out on the bow to keep from standing the boat upright when accelerating from a dead stop, you will likely need to do the same. ( Hope this helps you, send us video)

Bob


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PostPosted: Sat Nov 23, 2013 1:42 pm 
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Location: Jaco, Costa Rica
You need some theme music for such a large motor on a TI. How about "Macho Man" from YMCA. :lol: :lol: :lol: :lol:
:roll: :roll: :roll:

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Adventure Island- 2014
Revolution 13- 2013


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PostPosted: Sat Nov 23, 2013 2:42 pm 
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Location: Sarasota,Key West FL
CR Yacker:
Big boats with loud engines, and Porsches ( I've had several) have a lot in common, maybe compensation for something else LOL.
Only real men have lock stock TI's and Prius's
I'm old now so I have to settle for a souped up TI and my Pontiac Solstice.
Here's my setup
Image

Bob


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PostPosted: Sat Nov 23, 2013 4:17 pm 
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Looks good Bob, you sold me on a smaller outboard for the TI/AI. Just don't get anything much bigger. Like you said, your return on your motor in regards to the TI is slim as you get bigger. Might as well skip the TI and get a regular boat if their going to go that route.

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Adventure Island- 2014
Revolution 13- 2013


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PostPosted: Sat Nov 23, 2013 5:34 pm 
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Thanks for all the good info Fusion. Sounds like you have a backup motor for same reasons I want one. I cant imagine getting stuck out in the gulf 12 or more miles offshore knowing I would have to paddle back in after fishing and diving all day without a serious backup plan. Here in Louisiana the winds can be pretty weak and unpredictable. I have looked at that Honda 2.3 as well as the Suzuki 2.5 and even the Mercury 3.5. Just haven't made up my mind yet but after reading your reply im sure its pointless to go with anything over the 3.5hp.


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PostPosted: Sun Nov 24, 2013 5:57 am 
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@Fusioneng--Bob, my remark was not aimed at you. I understand your desire for a motor on your boat--a reasonable sized motor.

Keith

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I sail: Biscayne Bay, Everglades to Cape Romano, Ft Desoto, Cedar Key

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein


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