Handling help-boat on its side

Captcheetah · May 24, 2004

Had my '88 Renken 19' out yesterday for the first time this year and had a strange thing happen. On my way back to the marina, the boat wanted to tilt hard on the left side. I was running about 30 mph and the boat felt like it was going to flip over on its side. My wife (135lbs) was in the passenger seat beside me, and I was driving (265lbs), no one else was in the boat. It has never done anything like that before and it didn't do it all day while we crusing around. I had her move to the bench in the back on my side, it caused the boat to level out and tilt a little to the driver side, I had her move to the middle and it balanced out the boat. In the off-season I have added a wakeboard tower and a Stingray fin (hydrofoil). We had one wakeboard in the tower and the wind was howling. The boat was full of gas and there was no water in the boat at all. I thought 1) maybe the wind was pushing on the wakeboard causing the problem but we had been driving in the wind all day and it hadn't done anything remote to what it was doing, but I was probably moving a little faster. When I slowed down it did make the problem less pronounced. 2) The hull was full of water and had all shifted to one side, but the boat was bone dry when I pulled the plug. 3) The hydrofoil had come lose and was causing the situation, but after getting it on the trailer the foil was secure as can be. Any help will much appreciated.

Johnson70 · May 24, 2004

Re: Handling help-boat on its side

I had a similar problem once, turned out to be the zinc on the motor not positioned in the right place, it was causing the motor to move a little bit. Try process of elimination if you haven't taken the zinc's off.....Pull off the hydrofoil, see if that helps, could be that too...

salty87 · May 24, 2004

Re: Handling help-boat on its side

i have a wakeboard tower and have never experienced anything like that. i'd continue to check the drive or steering.

Jdeagro · May 24, 2004

Re: Handling help-boat on its side

Captcheeta; What you are experiencing is completely understandable and explainable. The tower has changed axis point (balance point) of the boat and the board helps manipulate the boat pitch (port to starboard). You may have also changed props as it is apparent that you intend to use the boat for towing. The hydrofoil becomes much more influential on the boat handling as the speed increases. It helps some in getting out of the hole, but as the speed increases to crusiing speeds at or above 30 MPH it lifts the stern too much and forces the bow down. This cause bow steering, and the listing to port is a fuction of the hydrofoil exagerating the prop torq. Especially if you have gone to a SS cupped prop. It is called a torq list. The good news is that the problem is easily correctable. First remove the Hydrofoil! Increasing stern lift on take off with added planing surface(in this case a Hydrofoil)is good, but doing so directly in the center of the boat is not. You have created a stability issue. With extra stern lift concentrated in the center as opposed to the outer sides of the hull, creates a teeter totter effect. You are balancing the boat on the keel. Any extra side pressure will through the boat one way or another. Slowing the boat down helped because the boat setteled back down in the water a bit. Now, the reason for the hydrofoil was to help the boat plane, which when you are towing from the tower will become more difficult. If you were to tow the boat from the water level (low on the stern) the extra "drag" would not have the leverage effect it has when towing from the tower 7' higher. The tower acts like a leverage arm to lift the bow. I am not saying that you should not use the tower, but you will need something ( Trim Tabs) to keep the bow down. We have published a tech bulletin on boat balance and performance which you are welcome to have. You may call 800-233-0194 or email John@Nauticusinc.com. We manufacture Smart Tabs and I suggest you do a search on this site to see what others say regarding the performance enhancements. They are fully automatic and continuosly active. Use # ST1290-60 available here on iboats.com

Captcheetah · May 24, 2004

Re: Handling help-boat on its side

Thanks John, that makes sense to me. I investigated your tabs before I bought my second hydrofoil, but in the end I was more comfortable drilling holes in the cavitation plate than the transom of the boat, plus I had good results with the hydrofoil on my last boat. But after the ride I took yesterday drilling holes below the water line doesn't seem so scary anymore. The hydrofoil comes off tonight. Anybody needing a hydrofoil, I have one for sale, used only once. Do I need to fill in the holes in the cavitation plate?

Captcheetah · May 24, 2004

Re: Handling help-boat on its side

Thanks John, that makes sense to me. I investigated your tabs before I bought my second hydrofoil, but in the end I was more comfortable drilling holes in the cavitation plate than the transom of the boat, plus I had good results with the hydrofoil on my last boat. But after the ride I took yesterday drilling holes below the water line doesn't seem so scary anymore. The hydrofoil comes off tonight. Anybody needing a hydrofoil, I have one for sale, used only once. Do I need to fill in the holes in the cavitation plate?

Boatin Bob · May 24, 2004

Re: Handling help-boat on its side

I agree with everything John said but before you remove the stingray did you try trimming the drive up to help with raising the bow and lowering the stern?

Jdeagro · May 24, 2004

Re: Handling help-boat on its side

Capt. and Bob; Please understand that I believe that hydrofoil Technology is valid, however it must be carefully integrated into the overall design of the hull. DHadley is very knowledgeable in this area and points out that the engine is likely to need adjusting up so that the foil is above water when the boat is at speed. The problem with putting them on I/O's is that the engine can not be adjusted up. A foil running below water can easily become a rutter. The best feature Smart Tabs has to offer is that they not only adjust themselves but can be further tuned to the specific boat. As for using the tilt trim to bring the bow up or down, this should be a fine tuning adjustment not the major source of attitude adjustment. Remember that the prop is most efficient when it is running perpendicular to the water surface, not at an angle.

Captcheetah · May 25, 2004

Re: Handling help-boat on its side

Do I need to fill the holes in the cavitation plate?

suzuki115 · May 25, 2004

Re: Handling help-boat on its side

Yes, fill the holes in the cav plate, 5200 sealant or 2part epoxy. Sand smooth after it sets up.

Captcheetah · May 25, 2004

Re: Handling help-boat on its side

Now that I think about it, the problem came after I had trimmed it down some due to some rough water. The wind was kicking pretty hard and the water was pretty rough (for a lake). I did also notice that the movement of the bow wasn't quite as pronounced at what I remember when I trimmed it up. I can always feel the bow coming out of the water when I start to trim. I don't have a trim gauge so I usually stop when I don't feel it moving up any more, and when I see my speed not increasing any more. Can the problem be negated with trimming the outdrive? Does the fin provide less lift as I trim? It seems like it would get to the point as I trim up where it would no longer provide lift and begin to actually create downward force and drag, like the bill of a crankbait.

steelespike · May 25, 2004

Re: Handling help-boat on its side

I have had very good luck with Doelfins and Ill bet trim could be adjusted for best performance and handling for each weather condition.It may turn out you are better off without the fin but give it a try.

Jdeagro · May 26, 2004

Re: Handling help-boat on its side

Captancheeta; As stated before the hydrofoil must be carefully integrated into the overall boat design. If the foil is running below water it will react much different than if at water level or above. Tilt and trim will affect the foil and the performance because you are changing the position and attitude in the water. The problem is that the boat attitude and water conditions also change costantly and the foil will react accordingly. Apparently your boat hull is more suseptable to these changes. For a test, simply remove it, replace the mounting screws into the cavitation plate with the nuts on top, and screw heads down. Go run the boat and make note of the various handling situations. The boat will not plane as well but the handling at cruising speeds is the issue for now. If the boat gets better then you know the answer. Now when you are ready, look into trim tabs ( Smart Tabs) which are completely active, self adjusting, and automatically react to the running conditions. Do a Search on these forums for more info and test results.

Captcheetah · Jun 1, 2004

Re: Handling help-boat on its side

Ok, took the fin off, I still have a torque list problem, not as pronounced but still have a problem. This is strange as I do not remember having any such impact last year with the boat. I didn't buy the boat until a week or so before Labor day weekend last year. We only had it on the water three to four times before storing it for the winter. I am running a High Five prop (19), I did change out the prop as soon as I bought the boat. The open throttle rpm's on the prop were right on the money. Is there anything I can do to help myself out? I did notice a drastic impact with the planing without the foil. I think I remember seeing on the package torque stablizer's that can be mounted on the fin. They appear to be small vertical fins that attach to the ends of the fin. Are these for my situation?

Jdeagro · Jun 1, 2004

Re: Handling help-boat on its side

I think you are missing the point. The torque list is caused by the prop rotation (clockwise) and the boat attempting to "unwind" in the opposite direction. The hydrofoil pushes the bow down at crusing speeds, and when the bow and keel are too far in the water the boat will lean and steer in the direction of the list. In other words the foil is exagerating the list. Re-installing the foil and adding steering fins to the foil is another bandaid. You can spend the summer playing with this, but you may never get it right using the foil. Your boat is a perfect candidate for Smart Tabs. Or helm controlled tabs, but then you will need to learn how to use the motor trim, and the trim tabs together. Call if you wish: 800-233-0194

Handling help-boat on its side

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