12ft. tinnie. boat with a 20hp chrysler on it...

jabboo

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Joined
Jan 23, 2002
Messages
16
i took it out for fishing last weekend <br /> and it went sweet <br />i got the boat to plane a couple of times with only me and one passanger in the front <br />( the boat is tiller steering )<br />the passanger is to make the bow of the boat come down.<br />when it planes the boat absolutely flys and the speed is awesome.<br />but with 3 people in the boat it doesnt plane and the boat goes allot slower<br />anyone know how to make it plane eaiser?<br /><br />and another question is would it be safe to drive this boat by myself without anyone else in the boat ( tiller steering ) is there any danger of the boat flipping over ? <br />or will it plane before it tips ?
 

Ross J

Lieutenant Junior Grade
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Nov 30, 2001
Messages
1,119
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

Hi Jabboo,<br />First I think to make it plane with three people you'd need more than 20hp.<br />Second, yes it would plane fine if on you're own if you place a sack with about 30-40kg of sand way up front. Experiment with the weight and you'll find it works a treat (40kg way up in the bow is like having 100kg on the seat)- I used to use a large water container that way I could fill it at the ramp and empty it after each use this way you don't need to tow around the weight on the trailer.<br />Ross
 

wippb

Petty Officer 2nd Class
Joined
Dec 3, 2001
Messages
171
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

One trick I used to do is put a longer hose on the gas tank and place it up front. Works best when it's full though.
 

jabboo

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Joined
Jan 23, 2002
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16
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

do u think i would be able to drive the boat from the back with the tiller without any weight in the front <br />besides the fuel tank in the middle ( only 23kg when full )<br /><br />also when i plane out will the front of the boat still stay up in the air or will it come down ?<br /><br />is there any danger of tipping the boat if i am the only one in the boat ?<br />( 12ft tinnie 20hp motor )
 

ebbtide176

Commander
Joined
Jan 22, 2002
Messages
2,289
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

try adjusting the motor tilt pin
 

evin300

Petty Officer 1st Class
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Jun 4, 2001
Messages
384
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

Heavy motor in proportion to boat. A doel fin for small motors should solve this. Trim will probably have to be set at neutural to negative with the fin. Without the fin, you may need wedges to produce extra negative trim, or as an alternative to the fin, you could use the cheaper self adjusting afterplanes or trim tabs as they are sometimes called.(Overtons) A "doel fin" is the cheapest alternative.<br /><br />I have not used the self adjusting afterplanes, but they look like a good idea. I, personally do not recomend using ballast in the front of the boat, overall performance and fuel economy are greatly affected. <br /><br />In your particular case, ballast may be an exceptable alternative, it all depends on just how badly this boat is out of balance.<br /><br />Just so you know, I have experience with a heavy stern condition (click on my profile) My 21' boat can deal quite well with a extra large motor. I have experimented with all of the above, plus more! Just so you realize that IMHO your rig with that horsepower has the potential to be quite dangerous.<br /><br />It seems to me, that you will have to stay out of the throttle alot, but the temptation will still have its day. Good common sense can solve alot of problems. You may even limit the throttle mechanically. 2-strokes like to run towards the maximum RPM, so your motor wont be happy with this, plan on a shortened engine life. But you can use carbon cleaner dilligently,to help offset this.<br /><br />Matching horsepower to your boat is quite important, as you can see. Not trying to bring you down jabboo, others may totally disagree with me. I just dont want you or anyone else to pay the ultimate price, boating in itself carries a certain risk, I just want to let someone know, when I think they are multipying that risk. Take Care, and good luck!
 

62_Kiwi

Lieutenant Junior Grade
Joined
Jan 20, 2002
Messages
1,159
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

Hi Ebbtide - down here in New Zealand and Australia (where from this angle the good ole boys look like northerners - no offence intended ;) ) the word "tinnie" has two meanings; 1). An aluminium boat, or 2). A can of beer.<br /><br />So, depending which way you look at it, a "tinnie full of tinnies" is either a good way to spend the day or a boat full of trouble...<br /><br />Jabboo - just be carefull (as a skipper always should be) of the bow getting too high when heading into gusty winds. Boats have been known to flip over with a decent sudden gust of wind that way. As always, its a combination of the conditions, the balance of the boat and most importantly the common sense of the skipper.<br /><br />I know from personal experience that the winds can get extremely strong very quickly in Sydney. BTW - Sydney is a fantastic city.
 

wakatoa

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Joined
Nov 26, 2001
Messages
24
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

Giday Jabboo, I think what you need is a tiller extension, you can then sit in the middle of the boat and steer and operate the throttle. Some OB makers have them as accesories or you can make one out of a piece of pvc pipe. This also allows you to stand up while driving (be careful) and keep a better lookout for fish etc. Also experiment with the trim on you motor, on my boat it goes fastest with motor trimmed upward to the max but yours may need a different setting. Good luck.
 

Pursuit2150

Chief Petty Officer
Joined
Dec 3, 2001
Messages
553
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

What puzzels me on these responses,and no one has asked. how fast do you expect to go in a 12' tinnie??, this is not a RACE. Yes add a tiller extension to help the wt. balance, but'<br /><br /> "KEEP SAFeTY AS A PRIME CONCERN"!!!
 

evin300

Petty Officer 1st Class
Joined
Jun 4, 2001
Messages
384
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

Jabboo, please do not add a tiller extension, it will only delay your responce time, I mean really, look how much further you will have to swing the tiler for the same result.<br /><br />This tiller steering, with a overpowered boat is a real bad idea. Look jaboo, you are going to have to decide whether you want to fish or ski, this boat, no matter how re-enforced it is, only displaces so much water.<br /><br />In an earlier post, you describe your boats previous life with a 6hp motor, and now you are going to increase the horsepower by over 200%?<br /><br />Let me tell you a story, my brother was almost killed when he and dad went fishing in a 12' "Tinnie" (I could care less what this thing is made of, its still a 12' boat) We had always used a 6hp motor, but we were on vacation and were borrowing a 9.9 hp.<br /><br />This boat was flying right along with two adults, my dad, who has used a small "Fishing" boat all his life, let go of the tiller, for just a second, to light a cigarette. He was at full speed, and the motor seemed very stable.<br /><br />Well, guess what? The motor shifted to a FULL turn, and immediatly tossed my brother out of the bow of the boat, untill then, he was great for BALLAST! Of course, no life jacket, and heavy clothing to boot! Dad barely hung on, and was stuggling for control as he ran over Duane, just as he was struggling to surface, luckily, Duane was concious, and used his hands to protect his head as his hands were severly cut by the propeller.<br /><br />Please keep in mind that we are talking about a 12' boat with a 9.9 crankshaft HP!<br />Friends, these little aluminum boats aint no "Boston Whaler". I have seen many experienced posters pipe up about horse power ratings, as if a 125hp on a 18' boat is dangerous, compared to a rating of 115hp recommended.<br /><br />Lets put this in perspective, a 200% increase in horsepower on this 18' boat would be 345 Horsepower! yet no-one is piping up, to help warn jabboo!<br /><br />jabboo, you want to ski with this thing? and pull tubers? I hate to say it, but youve got the WRONG boat. You have a small fishing boat, with a narrow beam, which if PROPERLY set up, will actually plane, with two full sized adults, on a good day, with the wind at the stern.<br /><br />I have not seen your boat, but unless it is some super-boat, like a "Whaler", then you are asking for BIG trouble. Jabboo, if you want to tow and ski, you will need a much larger boat and motor, which would include a steering wheel.<br /><br />Now, I would like some support, from other experienced boaters on this board, I am only one voice, and can be easily written off. IMHO, jabboo is on the wrong path, and needs some real good advice!<br /><br />Please feel free to disagree, but please, back it up with real life experience, not just speculation, there is too much on the line here. I appreciate my brothers presence, so much more now.
 

jabboo

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Joined
Jan 23, 2002
Messages
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Re: 12ft. tinnie. boat with a 20hp chrysler on it...

thankyou to all on this board for your opinions <br />i have tried adding a extension to the tiller witha pvc pipe and a hose clamp.<br /> but took it off about 5 mins after i entered the water with it as i knew it would be dangerous if i needed to make any quick movements because the amount you need to turn it its a huge factor compared with the normal tiller.<br />i am not doing that again, just to be safe.<br /><br /><br />i will try adjusting the pin to get the right angle. but i dont think i will worry about trim tabs or anything because i have realised the danger you are pointing out to me and am greatfull for your feedback and concern.<br /><br />thankyou to evin300 for all your input.<br /><br />one more question i would like to ask is would a cheap hydrofoil help at all to keep the bow down ?<br />does it help alot or is it just speculation ?
 

ebbtide176

Commander
Joined
Jan 22, 2002
Messages
2,289
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

hey jabboo i've got a fin on my bigger boat, didn't even think about one for my river boat. if i find a link, i'll let you know. i kinda thought they were only made for larger motors. they work great for getting you on plane, and from the other comments, i guess it will help keep the bow down on your tinnie also. <br />take care.
 

jabboo

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Jan 23, 2002
Messages
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Re: 12ft. tinnie. boat with a 20hp chrysler on it...

http://www.biasboating.com.au/hydrofoils.html <br />is near me and sells hydrofoils for boats with a power rating smaller then 50hp.<br /><br />would this help <br />this is it <br /><br />LZ Hydrofoils For Outboards to 50 H.P. <br />Cat. 3406 Per Pair $19.50 <br />Each foil is 180mm wide, 190mm fore and aft.
 

wippb

Petty Officer 2nd Class
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Dec 3, 2001
Messages
171
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

Jabboo<br />I agree with evin300's advice. The 12' that I had was powered by an 8HP. My brother and I fished in it often and had no problem getting on plane. A buddy of mine has an old 14' with a 25HP on it and it is down right scary to drive at WOT.<br />Be careful<br />Just my $0.02 worth
 

Raghauler

Petty Officer 2nd Class
Joined
Sep 5, 2001
Messages
161
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

I agree with evin300... BE CAREFUL!!!<br /><br />I had a 12' Sea Nymph "tinnie" with a 6 HP Evinrude for a short time that had no problem coming onto plane in calm water with two adults AND two children (spread out for ballast, of course), and I weighed 275 lbs. at the helm. No, it wasn't a rocket, but it wasn't slow either... we SAFELY got to the holes and caught a lot of fish with it. 12' tinnies don't need a whole lot to push them.
 

evin300

Petty Officer 1st Class
Joined
Jun 4, 2001
Messages
384
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

Hey jabboo, that hydrofoil looks like a winner, I think you will be impressed with its ability to keep the bow down. I have used one on my big motor, and they work very well. Thanks for the kind words, Take Care, Mike
 

jabboo

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Jan 23, 2002
Messages
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Re: 12ft. tinnie. boat with a 20hp chrysler on it...

thanks for your input once again evin <br /> i will go down tommorow and grab it and install the hydrofoil onto my cavitation plate<br /><br />another question<br />my cavitation plate is not inline with the bottom of the boat it is about 5cm below the bottom of the boat<br /><br />ive heard that the cavitation plate hsould be inline with the bottom of the boat but does the 5cm really matter?<br />what effect will it have on the boat?
 

ebbtide176

Commander
Joined
Jan 22, 2002
Messages
2,289
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

height of motor is really a hot topic to speedboaters, and a jackplate is often used to adjust this diff for max perf... i think your only concern might be for it being more apt to hit structure, unless you're gonna try to set a new speed rcd :D
 

ebbtide176

Commander
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Jan 22, 2002
Messages
2,289
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

jabboo, forgot to thankyou for the info on hydrofoil :D i'm looking into getting a propguard/skeg guard/foil all-in-1 type deal(check prop guard post) for my 12ft. 1 thing to think about with 2pc foil vs 1pc is that they match well when mounted. my glass boat has a 1pc for that reason. if you've already gotten the foil, let me know how it looks,since its 1sizefitsall<50hp, i was afraid it might need major adjstmt to put on...
 

evin300

Petty Officer 1st Class
Joined
Jun 4, 2001
Messages
384
Re: 12ft. tinnie. boat with a 20hp chrysler on it...

I agree with ebbtide, jabboo. You are close enough.
 
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