water coming over back of boat

T

trophyred34

Cadet
Joined
Aug 21, 2002
Messages
13
I have a 17'3 bayliner trophy center console. if i barely trim my motor water comes over the back of the boat into the spill area and if I trim it up to make that stop then the boat starts porpasine(the front bobs up and down) It seems that their is no happy medium,the holes in the spillway wont dump the water has fast as it comes in,and then gets in the boat.It has a 90hp force on it and the year is 97...I dont know how to correct this problem... :confused:
 
R

Reel Appeal

Chief Petty Officer
Joined
Aug 19, 2002
Messages
566
Re: water coming over back of boat

Hi John,<br /> How much transom is showing(from the outside)while your sitting still?Are you overpowered?What is the maximum recommended horsepower.(should be a plaque/sticker near helm area).If you don't think my questions have anything to do with the problem you may want to consider a bolt-on hydrofoil,such as a doel-fin.This product raises the stern of the boat slighty when moving and claims to help stop squatting/porpoising etc. :confused:
 
G

Greg Lawrence

Petty Officer 1st Class
Joined
May 18, 2002
Messages
263
Re: water coming over back of boat

id do the fin to every motor.. who set your motor up to begin with?
 
T

trophyred34

Cadet
Joined
Aug 21, 2002
Messages
13
Re: water coming over back of boat

It is raided for a 90 hp max, dont know how much transom is showing really, I always heard that the hydra foils reduce speed and also void warrenty work.but I dont have warrenty left so I guess that would not matter...I boat the boat used and the only place that sells them I e-mailed and they said we have no Idea what you are talking about and would have to bring the boat in so we could test drive it at a slight fee,I have never seen a slight fee at a boat dealership.. :rolleyes:
 
O

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: water coming over back of boat

check to see if cavitation plate on motor is roughly flush with bottom of boat.You'd be surprised at how many are not properly installed.If mounted too high it will tend to throw water in splash well,and also cavitate when hard throttled from a hole shot even when trimmed down.If that's not the problem i would follow the whale tail advice application.Good luck
 
S

sfels

Seaman Apprentice
Joined
Jul 25, 2002
Messages
43
Re: water coming over back of boat

The 90hp Force shouldn't be a problem for your Trophy. You might want to check your weight distribution on the boat. Do you have any extra weight in the back like downriggers or fuel tank for the kicker? If you have a kicker, you are adding weight at the transom which would put it lower in the water. If you have passengers on board, have them stand (or sit) further up towards the center console.<br /><br />Since the Trophy is a deep vee hull, I'd advise against adding a hydrofoil. With deep vee hulls they can cause steering problems and can actually cause the boat to tip easliy when turning on plane.
 
F

ForceHeadache

Cadet
Joined
Aug 12, 2002
Messages
26
Re: water coming over back of boat

Steve F - you mentioned a "deep v hull". I have a 16ft Bayliner Capri with a "V" hull (1985 model). Is this considered a "deep V hull"? I was going to get a hydrofoil for my motor this week, but with what you said, I am a little concerned it might upset my boat.<br /><br />Your thoughts?
 
J

Jango

Petty Officer 2nd Class
Joined
May 15, 2002
Messages
132
Re: water coming over back of boat

I have a 17ft Bayliner Capri, 85Force with a Hydrofoil (Dol-Finn) and it works GREAT. Able to make wide open turns and Boat feels Very Safe.<br />I believe a Hydrofoil will help your back wash problem.
 
D

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: water coming over back of boat

Check to see if the motor is mounted to LOW.<br /><br />Good luck!
 
S

sfels

Seaman Apprentice
Joined
Jul 25, 2002
Messages
43
Re: water coming over back of boat

Jango,<br /><br />Here's what Mercury says about fins:<br /><br />Q: Can I use aftermarket "fins" to help my boat get on plane faster? <br /> <br />A: Using a product often referred to as a stabilizer fin is a modification of the gearcase that may change the manner in which the boat operates on the water. With the unit trimmed fully down (in or under), a reduction of the time necessary to get a boat on plane may result. However, some V-bottom boats using a stabilizer fin may exhibit a tendency to roll over far to one side as soon as planing occurs. The direction and degree of the roll will be dictated by prop rotation, weight distribution, and degree of trim under. The boat roll can cause passengers to be ejected. Trimming up or out can reduce or eliminate the roll. Because it is not possible to know how a given boat will respond to the use of such a product without thorough testing, Mercury cannot recommend that such products be used or not used. Also, use of these products may cause or contribute to the failure of the anti-ventilation plate on the gearcase. Failures caused, or contributed to, by modification are not covered by the limited warranty.
 
O

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: water coming over back of boat

the cavitation plate is the flat protruding area of the lower unit above propeller that directs the propeller wash .The rear of it is usually where your trim tab is mounted .It is also where you will be mounting a whale fin if you so choose.some dealers don't get every motor optimally mounted for each boat application ,so a visual check can determine transom height location.Plate should be roughly flush with the mean bottom of boat,plus or minus 1/2" or so.
 
E

epresutti

Chief Petty Officer
Joined
Aug 14, 2001
Messages
465
Re: water coming over back of boat

TexasJohn,<br /><br />I would take Dhadley's advice and check to see if the motor is to low. If the blunt part of the motor above the cavitation plate (horizontal fin above the prop) is in the water (below the water level when under power) it will push water between the motor and the transom.<br /><br />Is the water a spray (how misty is the spray) or is it more like a wave? If it like a wave between the motor and the stransom, the motor may be to low.<br /><br />Hope this helps.<br /><br />Safe boating to all.<br /><br />Cheers.<br /><br />emp.
 
J

Jango

Petty Officer 2nd Class
Joined
May 15, 2002
Messages
132
Re: water coming over back of boat

SteveF,<br /> I noticed the Merc Quote, "SOME MAY exhibit a tendency To Roll Over".<br /> Apparently my Baylner does not fall into the catagory of "SOME". <br /> The Merc info does not mention what type Hydrofoil was tested! I still would recommend the Dol Finn. <br /> Sounds like "Legal, Cover Your A.." to me.
 
T

trophyred34

Cadet
Joined
Aug 21, 2002
Messages
13
Re: water coming over back of boat

If the motor is to low, can they fix that ,it is more of a wash or wave not a mist,guys thanks for all the info....
 
T

trophyred34

Cadet
Joined
Aug 21, 2002
Messages
13
Re: water coming over back of boat

ok, went out their and looked at it. The bolts are set as far as the motor will go down, so it proberly needs to be raised....I called a Bayliner dealer and talked to the guy on the phone (not e-mail) and explained it to him..he said that might be the problem,I asked him what else could it be, he didnt know... 140.00 dollars to move the motor up one hole, if it needs to be moved up again then it is another 140.00 but he said they could proberly get it right the first time..so I asked him why didnt they get it right the very first time and he said Bayliner put the motor on......passing the buck....
 
D

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: water coming over back of boat

Once more --where is the cavitation plate in relation to the bottom of the boat?<br /><br />?????????
 
T

trophyred34

Cadet
Joined
Aug 21, 2002
Messages
13
Re: water coming over back of boat

Ok,OK, :D the plate when the motor is trimed down is below the bottom of the boat,I would say 5-6 inches...
 
D

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: water coming over back of boat

OK. Now we know. You have a 25" motor on a 20" transom. The motor has to come up the 5-6". Its very easily done without messing with fiberglass. use a manual jackplate from Bob's Machine or Cook Manufacturing. <br /><br />You wont believe how much performance you are going to gain. <br /><br />Good job!!
 
O

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: water coming over back of boat

definately too low John.Don't feel alone . dealer in 1983 did the same thing to my new boat.In my case I had to actually re-drill holes and plug/patch the old ones.Nothing like swiss cheese for a new boat transom.Anyway, hopefully in your case you'll be able to relocate with existing motor mount holes.Bright side of it is you'll also probably see an increase in motor performance.Good luck.<br /><br /> A drop of oil in the right
 
You must log in or register to reply here.
Top