Backflow problem?Setup?Swamping stern?

[slabbott]

I recently was given (well, asked to store longterm/he'll never want it back) my father-in-law's 1980 Champion bassboat with 150 Mercury outboard. We test ran the boat on his home lake. He informed me of a problem and showed me that with the motor trimmed all the way in the water it would cause the engine to cut out at start-up unless you trimmed it up so that the exhaust ports were out of the water. The boat is very stern heavy anyhow, and after showing me we were able to get on plane somewhat quick, and after the fact the boat ran well. When I got it home (with my wife and 5 year old daughter in it) I tried the same thing and,I guess by trimming it out too far, I nearly swamped us when the stern was pushed under the water (thank goodness I fixed the bilge). This was very scary for all of us. It seems that the boat should just take off even if trimmed down all the way (I would think that a 150 should put out enough compression for this not to matter). A new tilt trim system has been added and there aren't any stops in place to limit it (full down has the motor tilted back about 20 degrees). My father-in-law said that he'd had the boat to a marine dealer who said something about a backflow problem and that there's nothing that can be done about it. I thought about raising the motor a notch or two on the stern, and/or using a hydrofoil. I can't get my wife or daughter to go back and can't imagine facing my father-in-law and telling him that I sunk his boat. Is this a set-up problem or what? I haven't had the boat to a dealer and would like to remedy this without spending alot of money. This is my first bass boat. I used to have a stern drive run-about and never encountered such a problem. This is still a very nice, fishable boat, and I hate to just let it sit. God bless!!

 

[JasonJ]

Re: Backflow problem?Setup?Swamping stern?

It sounds to me like the motor needs to be trimmed out at start-up, and once running should be trimmed back in for take-off. Did you trim out, start it, and forget to trim in before taking off? If you trim it out and start it, will it stall if you trim it back in? It shouldn't. I would guess that you just need to trim it back in before you take off to prevent the stern from squatting too low in the water. If the motor is trimmed all the way in, the propulsion will want to force the rear of the boat up, getting it on plane quickly. If the motor is trimmed out, it will want to force the rear of the boat into the water at takeoff. Another question, do you think it is possible that the floatation foam has absorbed water over the years and is causing the boat to sit lower than it should? That is one possibility, and if so, it needs to be addressed because the boat will not stay at the surface if swamped if the foam is saturated. Does sound scary....

 

[Solittle]

Re: Backflow problem?Setup?Swamping stern?

You need to give us a bit more info. before you will get meaningful input. First how big is this boat and what is the max hp rating? Next where is the cavitation plate on the motor relative to the bottom of the hull?<br /><br />You may also have a problem with the motor as it should start without having to trim it up.<br /><br />And as Jason has mentioned part of the problem may be that the operator (you - -) need to get some experience with this rig before you go much farther or at least until you try to coax the family to go out again.

 

[slabbott]

Re: Backflow problem?Setup?Swamping stern?

I agree that I do need to get more familiar with the boat before taking the family back out and plan on doing so. The boat is a 17 footer and has the boat capacity plate max as 150 HP. I didn't think about the flotation foam. There is a spot on the back that has been siliconed and riveted together (maybe a result of leakage). The bilge pump outlet is beneath the water, which can't be good either. I guess that would entail disassembling the deck and scraping it all out and respraying it? Another problem is wake coming over the stern which entails goosing it a little after you slow down. I'm not sure where the cavitation plate is in reference to the bottom of the boat, but the motor looks as though it's been raised to the 2nd or 3rd notch out of 5 or 6 holes. I guess pride gets in the way when talking to the father-in-law about it. He was like "this boat's always had this problem, there was nothing the marine dealer could do about it, I learned to live with it, and you can too", so I'm trying to learn to live with it, too. He's had the boat since new and like all of us, learn to live with little glitches over the years instead of paying to have them fixed. Heck, I reach under my dash to turn my heat on every morning because I won't buy a new piece of cable to fix it. Bugs the heck out of my wife, but doesn't bother me. My friends agree that even in full down trim, you should be able to give it the juice and go, no matter what. The motor ran great wide open when we test ran it. I've fixed my own stuff all of my life and don't have the pocketbook to spend a fortune on this boat. <br />Thanks for the information. I am glad I found this site and board. I enjoy the company. God bless!

 

[JasonJ]

Re: Backflow problem?Setup?Swamping stern?

If there was a way to get a pic of it on the water so we could see it that may be helpful. If need be you can email* it to me and I'll post it on here for all to see. My email is on my webpage.<br /><br />*Doesn't mean everyone can send me pics to post here, sorry.

 

[BMDODGE]

Re: Backflow problem?Setup?Swamping stern?

well jason if it takes a couple of hours to download your mail... those aren't pic's of my boat !!! lol

 

[ekubuckeye]

Re: Backflow problem?Setup?Swamping stern?

Sounds like you are carrying water. I don't believe the bilge pump exit should be below water line. This could be a huge problem and if in the water now could be taking on water. I would guess you have flotation foam soaked or at least are carrying hundreds of extra pounds in the bilge. Can you see any water there?

 

[slabbott]

Re: Backflow problem?Setup?Swamping stern?

ekubuckeye, I didn't see water. The things under cover right now, but I removed the fuel tank after I brought it home back in the summer and fixed the bilge pump. Is the flotation foam visible or lined between the outer hull and inner hull?

 

[18rabbit]

Re: Backflow problem?Setup?Swamping stern?

I am guessing, the bilge pump’s thru hull is not fitted with a shut-off valve, either?!? If not, this is a disaster waiting to happen. A bilge pump port below the waterline can act as a siphon if there is no means to prevent it. If there is nothing else you do, fix this!<br /><br />Below waterline fittings are used primarily for head holding tank discharge and occasionally gray water discharge. Plumbing for these has loops above the waterline and anti-siphon critters in the discharge lines. It is required they also be fitted with a ¼-turn shut-off valve.

 

[Uncle Dave]

Re: Backflow problem?Setup?Swamping stern?

Fisher,<br />As stated above, the hull or liner may contain water.<br />A test , when on the trailer, is to raise the bow and then lower rather quickly. Then listen carefully for a water gurgling sound . This is water running from front to rear or vise versa. Pick a quiet location to do this. If no sound is heard it is not conclusive that there is no water. But gurgles mean big problems.<br />Fitz.

 

[JasonJ]

Re: Backflow problem?Setup?Swamping stern?

Another thing you can do is weigh the boat at a truck stop or whatever. Then research the boat to find what the weight should be. Also research the outboard weight. I would guess the hull to weigh around 1000 lbs, and the outboard somewhere around 400 lbs or more. I am also guessing that fully rigged the boat shouldn't weigh more than 1800-2000 lbs. If you take it to the scale and it says it weighs like 3500 lbs (trailer will add 300-500 lbs so remember that) then you definatley have a waterlogged hull.

 

[Solittle]

Re: Backflow problem?Setup?Swamping stern?

You mentioned a riveted spot - Is this boat alumnium or fiberglass? That will make a big difference.<br /><br />Yeah you might could learn to live with the problem, assuming that it is at lewast safe, but it would be a heck of a lot nicer to fix it and have the family actually want to go.

 

[slabbott]

Re: Backflow problem?Setup?Swamping stern?

Solittle,<br /><br />The boat is fiberglass. There is a piece of metal trim that spans across the stern that looks to have been removed and re-riveted and/or siliconed underneath. So I'm getting the picture that waterlogged flotation foam is not something I can do anything about? I'm beginning to understand why my wife's dad gave me this thing. LOL I think he wanted to sell it, but wasn't going to get anything out of it. He also didn't have room for this and his jonboat at their new house. He's a river troutman now. I really appreciate all of the advice from all of you. I also appreciate the fact that there's not a lot of foul language and unnecessary inuendo. . .just good talk about boats and fishing. God bless!<br /><br />P.S. Jason, as far as taking pix of the boat in the water, it may be a week or so. We had 5 inches of snow this last weekend and my yard is kind of soft right now. I'll try and get some of it soon.

 

[JasonJ]

Re: Backflow problem?Setup?Swamping stern?

If its just a trim piece then I doubt it is an issue. The foam problem can be resolved, but it involves removing the liner, foam, refoaming, and reassembling. It is a lot of work, but not an impossible thing.

 

[ekubuckeye]

Re: Backflow problem?Setup?Swamping stern?

Sorry to hear about your troubles. That is one problem boaters hate to see. Flotation foam can be removed but you have to seperate the hulls. Anyone know of a process to dry out the foam by using a heated fan/forced air?

 

[wallbanger2]

Re: Backflow problem?Setup?Swamping stern?

I don't believe there is anyway to dry out the foam. The foam will want to hold onto as much water as it can because of the "closed" cell structure of the foam.

 

[LubeDude]

Re: Backflow problem?Setup?Swamping stern?

OK, <br />after all that was said, Ill give my input.<br /><br />Bass boats normally sit heavy in the stern due to the gas tank and the batteries are all back there. Try only filling the tank about half full when you are not going to need the extra fuel. Ive been around bass Boats for many years, and every one I ever had or road in had a backwash problem, You will always have to goose it a little as it settles down to keep it from washing over the back of the boat. Eventually you will figure how this particular boat wants to be shut down. Trimm up the motor and start it and then trim it back down as Jason said.<br /><br />I dont think you have a flotation problem! Been wrong before though.