cavitation problem

[silkeysak]

you may be getting blowout from that stock lower unit. get a shorter midsection and a bob's nose cone w/ low water pickup .you shouldn't be getting blowout till the mid seventies, but overtrimming might cause it. don't get discouraged. sometimes it takes a year, possibly two to dial in a proper setup. by the way, i have a red viking just like your boat with evinrude 225 looper. good luck p.s. how does that tank set forward affect your handling? does it chinewalk?

[buddhaboy]

i thought i would put the 12 gallon tank up front to keep the bow down on take off for wake boarding. Is chinewalk, when the boat starts to rock from side to side? because this is my problem, i thought it was called cavitation. heres what happens- i have great take off and the boat jumps right up on plain, at about 55 mph it starts to get a little loose , but still feel in control of the boat running about 4400 rpms. as i start to trim up my speed will incease to 62mph and rpms at 5000. the boat gets real loose and starts rocking a little from side to side. at 65 mph and 5200 rpms its scary and im having to get off the gas to gain controll again. i feel like its got alot more at 65 and 5200 rpms. Do you think i should 86 the tank up front move it back to the rear off the boat? i also have two batterys mounted evenly on a switch just under the dash up agaist the rail that sits before the tank i installed. i am short on cash right now and will be saving for a 20 mid and shaft. I am a beginer to hydrostreams, but not to boating. This boat is my baby and have big plans for her over the next couple years. I love the look of the viper and this boat a 1975 released and bought from the original owner in 76 my birth year. the core will get replaced the winter and is in not to bad of condition do to being garage keep for its life. I got the johnson 150 because it was like new and had low hours from a family friend witch sold it to me for cheep because i was moving. i also have a yamaha 115 v4 with a new power head and 20 inch shaft. when i had this motor on it would run 62mph without a jack plate, but this motor is tired and takes a little to get up on plain. Thanks again everyone Jason " not even close to giving up yet,i will get 80 out of this boat some day"

[77viper]

First and foremost I wouldn't go any faster than I wanted to crash at Before Replacing The Core. I'm not saying it will happen but there is a good possibility of delamination with a unknown core. Here is a delaminated core. Not Mine just a picture I found, but you can see what can happen with a bad core, the glass just peels away.


As far as chine walk, you need dual cable steering as well as solid motor mounts. My vegas was bad at first even with dual cables, I went to hydrolic steering that helped, then I went to solid mounts and that helped to but the big thing was getting the motor up.

[hydrostream76]

with the chinewalk you do have to anticipate that and try to countersteer a bit...
but in your case it will be even more exagerated because of the length of your 25" midsection
i've had my motor at its lowest and highest on my transom lift and it wants to walk like mad at the low point
at the highest point it's almost effortless , and could go higher, but my lift was put on too low.
so i can imagine how hard yours would be to drive at high speed,
you're stuck unless you go to a 20" mid or if u got cash a 15
there's not much u can do with that engine than what it's doing now
and you don't want your tank in the front ....
go to a 19 pitch if u want to ski with it
you can have the boat loaded and it'll get skiiers up ...
nice wheelies too .... lol

[buddhaboy]

thanks. re-doing tank this week to lighten the bow. it just sucks because i love going fast and pushing the void on everything i drive from my bike to my quad to my viper. i will keep trying for a 20 mid and shaft and then get a bobs nose cone and lwp with a chopper but, after my recore this winter. should have a good amount of time to save some money. just like anything going fast takes time, good advice, hard work and determiation. not giving up , think i will try to set up what i got in a safe manner , enjoy the boat and go for speed later. oh i like wheelies have a 19 never thought of putting it on

[silkeysak]

Hey man, what you're describing is a severe chinewalk. That tank and batteries forward is very likely the problem. The pivot point on these boats is about 12" forward of the transom. But don't worry, when you want to pull a skier drop down to a 19 pitch prop. Problem solved. You may also want to add some 6 degree negative wedges between the motor and jackplate. These cost about 45 bucks and can be found at Bob's machine shop. While on their website check out their nosecones AND a torque tab. The tab will get rid of torque feedback in the steering, and between the tab and cone you're stability at high speed will be like night and day. I have run a 16' checkmate w/200 rude and 18' action marine w/ 200 rude and with this setup the both tracked beautifully. The viking w/ 225 looper I'm currently putting together (will be in the water in about two weeks) will get the same treatment. I am fully confident in this arrangement. It took me almost two years with the checkmate to figure this out. They are notorious chinewalkers. By the way, those negative wedges give more negative trim for getting on plane. Because of the bowlift created by your hull design, you'll still have PLENTY of positive trim. At full throttle you want the boat as parallel to the water as you can get it but still keep it freely broke loose and on the back 12" or less of the pad. You'll have to get the feel by experience. You want the propthrust as close to parallel with the water as you can get it to get the max hp to the water. Show me a big roostertail and I'll show you an inexperienced driver. Unfortunately the local marina guys know little or nothing about setting up a fast modified v rig. Most of us (unless we were lucky) have had to learn the hard way, by trial and error. What sounds like the easy solution to a problem may open up another can of worms. You don't have to do much to fix your problem, but time behind the wheel and trial and error with motor height/ prop pitch etc. will pay off in the long run. Unfortunately that's the due you gotta pay if you want a fast stable ride. Good luck, happy to give my own humble opinion, for whatever it's worth. Some will agree, some won't, but it works for me without spending the big bucks. There is no better feeling than when you get it figured out on your own and the other guys eat your steam. Have a good one, I hope this helps.

[buddhaboy]

thanks slinkysake. so far i feel with out spending a bunch of loot $ , this is what ill try first . i already have the wedges and dual streering, thinking the tank is the problem. i will get back to you and let you know and everyone else who has helped. thanks again you all !!! love this site and the people on it!!

[buddhaboy]

HELL YES BLACKHAWKS!!!!!!!!!!!! SUCKER *** PHILLY FANS

[Hippie459MN]

HELL YES BLACKHAWKS!!!!!!!!!!!! SUCKER *** PHILLY FANS

Huh?? I think you might be in the wrong forum or something. LOL

[ Post made via Mobile Device ]

[buddhaboy]

sorry got a little excited, while reading about Hydrostreams and watching the match!!! working on the boat today..........