got the motor raised, now porposies real bad,now what....

[trophyred34]

Ok. guys, I got the motor raised and now the cavitation plate is about 1/2 inch from the bottom, water quit coming over the back, shots out of the hole good, but now it porposies real bad in calm water ... talk to the guy that did it,and he said that raising should work but he was afraid of the bobbing thing, said may try another prop, but I cant afford that, also trim tabs, or he thinks it might be a flaw in the desingh...97 bayliner trophy center console 17.5 ft with a 90 hp force....I guess I could take a gamble and put one of the hydrafoil fins on...what do you think...I cant afford 80.00 dollars an hour for these guys to keep guessing at what I should do ....thank for any info...

 

[Walker]

Re: got the motor raised, now porposies real bad,now what....

Now you need to lessen the trim or in other words kick the bottom of your motor in toward the back of the boat. If you have power trim and it won't go down any farther then you need transom shims. If you don't have power trim then maybe your motor stop pin can be lowered to the next hole.

 

[trophyred34]

Re: got the motor raised, now porposies real bad,now what....

motor is almost completly tuck under, if you trim up any it gets worse...

 

[Walker]

Re: got the motor raised, now porposies real bad,now what....

Where are you in Texas???

 

[trophyred34]

Re: got the motor raised, now porposies real bad,now what....

mesquite...

 

[DJ]

Re: got the motor raised, now porposies real bad,now what....

texasjohn,<br /><br />Porpoising is caused by the engines inability to hold enoigh of a bite on the water to keep the bow up, thus it rises and falls.<br /><br />Your engine is too high if it continues to porpoise with trim all the way in (negative trim).

 

[Reel Appeal]

Re: got the motor raised, now porposies real bad,now what....

texasjohn,<br /> Looking at the outside of your boat,look at the motor(transom)bracket.There may be a horizontal trim/tilt rod going through a pair of holes.Usually these rods can be removed and adjusted.Trim the motor up,remove the rod and put in holes nearest your transom.(unless your in the nearest hole now?).

 

[trophyred34]

Re: got the motor raised, now porposies real bad,now what....

Reel, the rod is already in the nearest hole to the transom, and as far as the motor being set to high, the problem is that before it was set to low, thus trading 1 problem for another...

 

[Reel Appeal]

Re: got the motor raised, now porposies real bad,now what....

john,<br /> With the motor in the down position.The cavitation plate should be level or even with the bottom of the boat.Slightly (1/2"or less)above the boat bottom is usually ok too.<br />Questionoes your boat seem stern heavy?(squatting?)Is it slow to get up on plane?If so,your hydrofoil idea is a good one.I recomend the Doel-fin myself.What is the maximum recommended horsepower on your Bayliner? <br />Also,try distributing weight forward/aft for better performance.

 

[Walker]

Re: got the motor raised, now porposies real bad,now what....

Just another possibility. Could your sub floor be full of water? Raise the tongue of the trailor as high as you can get it, even block it up to get it higher and pull the drain plug. Walker

 

[ob]

Re: got the motor raised, now porposies real bad,now what....

how much was motor raised from original starting point when problem was reverse of present symptom? may have to split the difference if present symptom is not related to the input from Reelappeal & Walker suggesting to consider weight distribution or waterlogged subfloor or transom

 

[naughtybynature]

Re: got the motor raised, now porposies real bad,now what....

your height is where it is supposed to be. something is not right though.... i think the guys are onto something with too much wieght in the stern. check for water in the sub floor and foam. you might have to ever drill a little test hole through the floor to see if there is water in there. raising your motor changed your center of gravity and now your setup can't carry the bow very well. a prop with more cup will do the job... but that is just curing a symptom of the real problem. remember that your boat is not exactly a deep v and most shallow v boats will bounce a bit in very calm water as the hull struggles to break free from the water. a little ripple helps ventilate the hull better.<br /><br />still i think your problem lies in wieght distribution because that hieght should be right for your boat. i think the reason it didn't bounce so much before is that your gearcase was so low in the water that it was actually pulling the bow down like a trim tab would do. now that drag is gone... <br /><br />a just put a hydrofoil on my kid's boat and it solved all planing and porpoise issues. it came with a money back garantee so i had nothing to loose. find one like this, it might help. but go after the wieght thing first.

 

[ob]

Re: got the motor raised, now porposies real bad,now what....

If it is water in subfloor or in transom problem it needs to be allieviated as dry rot will reek havoc on the structural integrety of hull,especially transom.Hopefully just need to redistribute weight in rig and or add a planing fin to motor.

 

[trophyred34]

Re: got the motor raised, now porposies real bad,now what....

No water in the hull, before the motor was raised it would dump water over the spill guard,very badly,the cavitation plate is about a 1/2 below the bottom, the motor was raise 2 bolt holes, maybe it should be droped down 1 and with the hydrofoil it will solve the problem, Hate to pay another 80.00 bucks to have them move the motor again..as far a weight dis. I have 3 batteries in the back, 1 for the cracking and 2 for the trolling motor. I will try the hydrofoil first,and if it does better them might have the motor droped 1 more hole...I think I can do this myself with a little help and a hoist, just cant pay 80.00 again...

 

[jancsikoerber]

Re: got the motor raised, now porposies real bad,now what....

I believe I might be ready for a simalar problem-i've just got a great deal on old 14ft alum v hull jon-with a 8hp honda age unknown -numbers on transom braket 1000584 ??any one out there with a way to discern the real year would be most helpfull-I know it is between 1988--1998-the problem is the hieght of the cavitation plate-this a 20 incher-the transom on the boat has "minnie jacker' already raising the motor up-and the cav plate still 3 + inches below bottom of boat -altho I have yet to give the real lake test-can I raise this minne jacker more? and how high can you go? before you find a new problemo??

 

[Bob_VT]

Re: got the motor raised, now porposies real bad,now what....

Djohns19 has the right reason, it is the inabilty to hold up the bow. Your not going to want to hear this suggestion but you may be propped wrong and it is not sufficient to maintain a bite.<br /><br />Bob

 

[steelespike]

Re: got the motor raised, now porposies real bad,now what....

I be tryen, You need to post your own guestion it will save confusion.

 

[trophyred34]

Re: got the motor raised, now porposies real bad,now what....

Ok guys, I put a stingray hydrofoil on and it did great... I have a 19 pitch prop and a buddy is going to let me use his 21 pitch prop to try out,,,dont worry already called the local prop shop and told him what I was doing and he gave me the Ok...both are motors are the same...I think the 21 will give me a little more speed...thanks for all the help.

 

[naughtybynature]

Re: got the motor raised, now porposies real bad,now what....

texas, a bigger prop isn't neccesarily the solution, a prop with more cup or rake will give you the bow lift you are looking for. when going to the bigger prop note engine rpm, if you are below spec, forget about the bigger one and go back to origional prop and get the shop to put more cup in it. i bet this gives you more bow lift, less porpoise, and MORE SPEED! yeehhaaa.