Boat Dives At High Speeds?

[gforceauto]

fIRST OF ALL ITS A 16 FOOT TAHATI. I am just getting it to go fast, and at aprox.. 80mph with my diverter trimmed out it seems like the front end is digging in. It has took an abrubt turn on me twice now. Any clues? Is my hull limiting me to that. I hope not i want it to go faster.
thanks T

[Ken F]

If it's taking an abrupt turn on you then you have some definate issues.
BE CAREFUL. Many people have been thrown through the side of boats that way.
I'm not familiar with your perticular hull, but just taking a SWAG I'd say you have far overdone it with that speed. Your hull was not ever designed to go that fast. Please be respectful of your wife/friends and only do speed runs lilke that when you are alone so that you don't kill a passenger!

[Oldsquirt]

That hull was never designed to go any where near that speed. The problem is the deep entry bow which causes "bow steer". Two friends have had that same hull, one with a 455/Berk and the other with an I/O. Believe it or not the jet(max speed about 65) never had any problems but the I/O did.
If you want to go fast/faster, find a more suitable hull.

[bp]

i'd guess you're running it out of water. nice shot of the side, but what's the hardware look like?

[W.O.T]

id be real careful things happen real quick at high speeds. id be scared to go 80+ in a little 16 footer.

[atxwrangler]

i would definately say the bow steer is coming from that deep v bottom!i would definately be looking for a tx19.

[gforceauto]

It is actually extremly smooth, i can almost take my hand off the wheel. It just feels like the fronts diving at a certain speed.
thanks alot T

[DUCKY]

Take a good look at the bottom. That bow steer situation is bad enough, but can be compounded badly by a hook in the bottom, and every small Tahiti I have ever seen, has a bad hook in it, and all the diverter in the world won't overcome it. I actually measured one that had a 3/8" hook right at the transom.

[kp216]

What the others have said about the hull are right.
I have an 18' CobraJet with the same style deep V entry. A very knowlegable boat rigger informed me NOT to push my hull faster than about 70 because of the danger of bow steer.

[SmokinLowriderSS]

80+ in a 16'er, dayum.................... I'm trying to get to mid 80's in my Taylor, which is risky enough, but she isn't displaying any warning signs yet of bad behaviors..
Your boat is talking to you. For whatever reasons, it doesn't want to go that fast, and probably shouldn't. I would consider listening.
What year is it? From some comparison photos I'm looking at:
http://www.teshio.com/JetBoat/tahiti.htm
The early '70's ones had a much steeper entry to the water at the bow (it's in heavy shade in your photo but yours looks this way) while the later models (75 and later), at least the ones shown, had the much flatter entry angle of the faster design V-hull jets.
Is it trying to hook-turn (hook the nose and spin) when you let off of it?
If so, the nose is held dry while running by the diverter thrust BUT, you reduce it, the bow drops, the entry catches the side of a wave, and arround you go, swapping ends.
This would be accentuated by hook in the transom pushing UP on the stern, and thus down on the bow. Get a 4' or longer straightedge/carpenter's level, etc, and lay it from the stern foreward and see if there is any "droop" at the back edge of the hull. This is what is called hull "hook".

[Duane HTP]

You need to talk to Texas Jet. He has a Tahiti with a bottom like yours. He can give you some insite on what to expect out of that boat. From my past expirence, I believe you've exceeded the safety of your hull. Yes, you can take the hook out and maybe go faster, but what the hell are you going to do when it comes time to shut it down?????? It would be worth your time to contact him. He posts here. Nice Guy to talk to.

[Bow Tie Omega]

I by no means am a hull expert. But when your boat wants to "dive" or turn suddenly at 80 mph without any input, as SS said, your boat is talking to you. If I were you, be happy with 75. If you are really into the speed thing and have to go faster, rather then working on a hull never made to do speeds that you are going, buy a hull made for it. Speeds above 80 is getting into a new league of boating and experts are coming on here and asking you to not do it. I would listen. There are some fast hulls minus motor for sale in the spam section for some very reasonable prices. If you really need the speed, go that route. WHile I am not a hull expert. I am an expert with seeing the results of high speeds gone awry coming thru the Trauma Room doors. Those results are usually a grotesque type of maiming, dismemberment or even death and any combination of the 3 which I have seen and cared for probably 200 times give or take. It is not something you ever want to see or have happen to you I promise you that. And everyone of them thought it would never happen to them.

[396_WAYS_TO_SPIT]

Easy on the 80+ in a 16'er. With the right hull 80 isn't a problem
Only for you crazt a$$ canadians:D

[fleetimus]

I have two boats. 16' cheetah and a TX-19 Condor. I had the 468 BBC in the Cheetah for a SHORT time. It hooked on me at 80 mph one time!!!! That is when I went looking for another hull. The TX is much better suited for the BBC.
For what it is worth, back off on the Tahiti. IMO, you are asking for a disaster!! The hull on the Cheetah is the same as the Tahiti.
http://www.hotboatpics.com/pics/data/500/4155HPIM0167-med.JPG

[Xerophobic]

Is it possible you have an agressive loader and you are getting reversion thru the intake at that speed? Do you have any pressure guages on your pump/intake?
it will tend to make the boat feel as tho its 'hopping' forward and the transom will feel like its lifting.
video would help
Cheers

[gforceauto]

thanks for the info, it is kinda like xerophobicsaid it just feel like its pushing the nose down, and no i dont have any presure gauges i didnt even know you could run one. I was going for stainless impeller and 150 shot of nos, but all you guys got me kinda scared to push it any farther. Although it still feel too slow to me. What is the hull of choice and does anybody got a pic of one. I am running a 500hp sbc and on a small lake. But i just shelled out 7000.00 on paint and interior so i hate to even think about it , but i goto ask.

[Duane HTP]

You would be a lot better off in a TX-19, gulwing or a tunnel boat like Cheyenne, Eliminator, or Stealth. There are other good tunnels out there too.
But, no matter what you do with your intake loader, you still have a Tahiti, and it's going to pitch your a$$ one of these days at those speeds. The hospital bill may make the $7000.00 seem like nothing when it's all over.

[Gearhead]

What Duane said! He is very right and the outcome will be much better with a good hull. Faster, safer and much cheaper than a bad trip to the hospital.
I'm glad these guys are standing up and offering good advise on safety at the same time when our desire is fun with performance.

[fleetimus]

If I would have had a passenger when mine hooked, it would have been very UGLY. It scared me so bad I idled back and did not run it the rest of the weekend.
The same engine in the TX-19 has hit 90 with total confidence. Friends told me if I didn't take that engine out of the 16" boat they were going to sink it before I killed myself!!!
Listen to these folks. They are right!!!!

[FILUCKY]

Bump your cam back 4*, you'll live longer!LOL

[Moneypitt]

Can I borrow your speed approximator?................MP

[ss396]

there are guys up here in the northwest running 100 plus on radar with their jets and doing it very safe. the boats they are running are made for that kind of speed. they are welded aluminum hulls and a person has a choice of either tunnel or v haul. i would go tunnel myself. i have drove both. we raced these on white water rivers at speeds of 80 plus in the rapids and smooth water. if you would like some pics and more info contact Riddle Marine in Lewiston Idaho and talk to Doug Riddle. i have drove these boats and seen what they can to and take. if you want a jet that is fast and safe i would not wrap myself in fiberglass. (i do have a v-drive sanger but i do not plan on doing the really fast speeds safety is number 1) you can also get vidio of the white water river racing and see how these boats fly. 65 plus in a tahiti is suicide with the hook in the bottom i saw one do a complete end over end and put the driver in the hospital for weeks and the passenger ended up in a wheel chair. need more said. lets all motor safe. over on the v-drive section there is some really good advice safety equipment ect take time to read it.

[gforceauto]

so where or who has the hulls? and 4 degrees back was no fun.
and as for my speed aproxomator just give me a ride and i'll tell ya.
I was radar'd at 65 and its much faster now.

[diggler]

I would consider listening.
What year is it? From some comparison photos I'm looking at:
http://www.teshio.com/JetBoat/tahiti.htm
The early '70's ones had a much steeper entry to the water at the bow (it's in heavy shade in your photo but yours looks this way) while the later models (75 and later), at least the ones shown, had the much flatter entry angle of the faster design V-hull jets.
The boat shown in the link (the white one with the blue checkered flag) is my old boat. It was an 18' 1972 Tahiti powered by an Olds 455. I had a top speed of about 74mph with it.
IT WAS THE WORST RIDE OF MY LIFE.
The boat porpoised and chine-walked at anything greater than 50mph. I had more than one incidence of bow-steer and it scared the living hell out of me. I ended up selling it and buying a 19' Ultra Shadow. I can run it at sub-100mph without any of these problems. Solid as a rock, as they say. Sell your Tahiti and get a hull that is designed for the higher speeds.
http://www.***boat.com/image_center/data/500/142DSC00141.JPG

[Sanger Jet]

You would be a lot better off in a TX-19, gulwing or a tunnel boat like Cheyenne, Eliminator, or Stealth. There are other good tunnels out there too.
But, no matter what you do with your intake loader, you still have a Tahiti, and it's going to pitch your a$$ one of these days at those speeds. The hospital bill may make the $7000.00 seem like nothing when it's all over.
This is why I'm looking for a better hull.......Before I KILL MYSELF !!!