Boat Leaning-newby question

[tcmers]

Well....we launched our 1970 Skiff Craft today with limited success. Developed some rough running problems about 20 minutes into our ride. We'll work on figuring those out. The problem we need some help with is that the boat leans to the right. When under power, this is pretty noticable. We tried balancing the load, realizing that the weight of the occupants in a 21' boat will effect this somewhat. Is there some flaw in the hull that could cause this? Or do we just need to work on balancing the load more. (other than the two of us, all we had in the boat was basic equipment and a cooler.) We looked under the floor, and there was no water on one side that would be causing this. Thanks.

[brad9798]

gas tank? water tank?

Two people on one side of a 20-footer will push that one side down between 4-10" depending on the boat ...

A lot of epoxy patches on one side???

[mmd]

tcmers, is the problem only evident when underway, or is the list present even when at rest?

[tcmers]

We were just out looking and analyzing. As we look at the boat, most of the furniture is on that side, the battery and anchor are on that side, and the driver out weighs the passenger by 70-80 lbs. We also noticed that the centerline of the engine block is set slightly to that side as well. The engine and outdrive are centered, but being an inline 4, the cylinder line is slightly off center. Probably not enough to make a big difference, but added to all of the other things.... We'll work on moving stuff around a little and see how it works.

[tcmers]

mmd, the list is present at rest, but it is minimal. Under power, it is much more significant, especially at high speeds. (20mph +)

[Donn]

I'd suspect something. IIRC, when you get on plane, the effects of a weight distribution listing will be diminished somewhat, no?

[mmd]

Shift or add weight until she rests on an even keel (passengers & pilot included), then test run again to see if the weight distribution is the real problem. If yes, re-arrange the internal gear (battery, fuel, stores, etc.) to correct the imbalance. If she still lists at speed even though the at-rest balance is right, let me know and I'll go the next step with you.

BTW, the motor motor being slightly off-centre will have a suprisingly small effect because the distance from the motor C of G to the boat centreline is so relatively small. Placing a 40-lb battery 2 ft. to the left will happily balance a 200-lb motor off-centre 3" to the right.

Let me know how the second round of trials goes.

[tcmers]

Thanks MMD. We're working on some rough running problems tonight (suspect fuel & filter) and hopefully will get another try yet this weekend. We'll let you know if leveling the load works out or not. After reading your comments, we're afraid it won't work because it seemed to get worse the faster we went. Wasn't too bad at 10-12 mph or so, but above that it seemed to get worse. Thanks again.

[Victor]

Even if you move stuff around to level it at rest, an imbalance like that could make the boat very unstable at speed. I think a good set of trim tabs is in order.

I once rigged up a pair of manual trim tabs to compensate for my weight when going out alone. You could set one to lift the starboard side. That might help but it would probably still be unstable. Perhaps you should put on a life jacket and go out by yourself to check out the various configurations, noting the possibility of a wild broach and a quick swim. Could be fun with the right attitude. But until I worked this out I wouldn't take any women or children out.

Never heard of a wood boat doing this, usually it's a glass one that's gotten saturated on one side.

[tcmers]

Never heard of a wood boat doing this, usually it's a glass one that's gotten saturated on one side.

Don't think it's a problem with the wood being saturated. The boat has been out of the water for at least a year, and was listing to one side as soon as we put in, and motored off. It's plywood lap construction, and didn't seem to have an abnormal amount of water in the bilge throughout the day. After launch, it was over an hour before the bilge pump even kicked on, and everything seemed dry up front when we looked under the floor. Not sure how much water a boat like this typically takes in after being out of the water for an extended period???, but we maybe had a couple of gallons in a few hours.

We were just discussing the trim tab option. The boat has two spring loaded tabs with no adjustment on it now. We were thinking that maybe the port tab has a stiffer spring, and is staying lower in the water, causing the list to starboard.

The stearing seems to pull somewhat to starboard as well. Does this indicate that the tab (trim tab?) on the outdrive needs to be turned in one direction? Thanks again for the input.

[Ian McColgin]

You've described some static weight imbalance anyway which could be planned for. Our club launches sit heeled a bit to starboard at the dock but come to their level marks once the launch operator is at his or her station on the port side.

That imbalance could become more critical at planing speeds, I suppose.

Another possibility at speed is the effect of engine torque. This should be apparant at rest as well. Try gunning the engine good and hard both in neutral and in gear to see if that makes her lean over a bit.

G'luck

[Jack Heinlen]

The stearing seems to pull somewhat to starboard as well. Does this indicate that the tab (trim tab?) on the outdrive needs to be turned in one direction?

This is likely due to prop walk affecting the feel at the wheel. Most power boats have a right turning prop. In an inboard this will tend to move the boat to port(think of the prop as a little paddle wheel). In an IO the same effect will want to push the lower unit to the right, perhaps creating an opposite feel of the boat wanting to turn to starboard.

[Domesticated_Mr. Know It All]

Lyman's have been known to have a problem with galvinized fuel tanks. The galvinization flakes off and cloggs the fuel system. A temporary solution is to change the fuel filter more often and keep a spare on board. The best long term solution is to upgrade to a new plastic or stainless steel fuel tank. I suspect your Skiffcraft might have the same problem. Just a thought. [img]smile.gif[/img]
Peace----> Kevin in Ohio

[mmd]

Hey, tcmers, did you have any success on the weekend with correcting the list problem by re-arranging weights within the boat?

[John Bell]

Jeff, that sounds like the "new" boat was chine walking. Is that a possibility here?

[tcmers]

mmd, We didn't have a chance to take the boat out. Still working on the mechanical problem. We're taking it in for service, and probably won't have it back until next week. I'll post the results when we get it back on the water.

Ironsawmill, To our Knowledge, the engine is the same as the engine that was originally put in the boat. Not sure if this is the original engine, but they left the factory with 140 HP 4 cylinder engines. Don't know about the rotation. We were on and off the throttle quite a bit at various speeds, and it din't make the boat rock from side to side. At any speed, the pull was to the right.

John, What is "chine walking"?

We're determined to sort this out. After talking over the launch day events, we believe that most of our problem is an issue with weight distribution in the boat. The boat did list at rest. Under power, it was more noticible, but on reflection was more of a steering pull than additional listing. A previous poster mentioned that two occupants in a boat this size can cause it to lean 4-10 inches. What we experienced was no where near 10", and probably was under 4" different from side to side. As I said earlier, more noticable at higher speeds, but was more of a pull to one side than an additional list. We'll get it running right, balance the load at rest and go from there. As suggested, we'll put a good set of trim tabs on as well, but not until we've done some additional testing with the current configuration.

[Paul Pless]

My experience with 'chine walking' is that it occurs at very high speeds with most, if not all of the boat, out of the water the majority of the time. What happens is one side of the boat will develop a condition in which the surface of the water begins to flow in a laminar like way accross the hull surface and will suck that side of the boat down. At some point the suction will break and this condition will rock the boat to the other side. Around these parts this is usually manifested on bass boats; think 1250 lb hull with a 250 hp outboard. Exciting! I have personnally seen a boat chine walk so violently and the onset was so unexpected that it threw a passenger out of a bassboat at about 60mph. I have also seen video of boats chine walking just before they flip over backwords. Perhaps these were unrelated events, however, I feel as though chine walking is a warning signal to me that my outboard is not trimmed correctly for the water conditions or the speed at which I am going and I make the necessary adjustments before things get out of hand.

[Victor]

tc, I think you need to assume this boat will never be very stable. Few hulls, even glass ones, keep their youthful figures into their 30s - who does? Mine goes on plane at 15, cruises nice as can be at 20, and starts yawing at 25, which is a) top speed for my motor and b) as fast as I want to go anyway. If you want more speed than that you've got the wrong boat. The trim tabs help - I prefer the manual ones - but should not be relied upon to compensate for a basically unstable hull. You're risking a big fat broach if you exceed the limits of your hull, which means leave the kids, the wives, and the parents ashore.

[tcmers]

Victor,

We have no intention of pushing the limit with this boat. Cruising at 15 MPH or so was very comfortable, and we see no reason to exceed that. Our guess, based on what we experienced is that somewhere around 25 is top end for this boat anyway. We bought it to cruise and fish, not ski or race. If the boat is stable under 20 mph, we will be VERY happy. May we ask the size/age of your boat? Thanks.

[ 07-13-2004, 08:02 PM: Message edited by: tcmers ]

[Victor]

Mine's a 19-foot, 44-year-old utility, a real sweetheart on the water. Course here in New Jersey, the Land of the Big Engines, that's not considered very fast, but the truth is any speed over 30 is uncomfortable and potentially dangerous. The boats you see screaming across the water are usually only doing so for a short time - just like on the highway.

[ 07-13-2004, 09:52 PM: Message edited by: Victor ]

[Jack Heinlen]

Hm. I'm a little stumped. The hull on this boat should not have distorted. It doesn't mean it hasn't, but the construction technique is superior. Distorting it would take serious neglect.

I'm kinda betting on the trim tabs. Are they standard on a boat like this? It's not engine torque, it can't be trim weight or it wouldn't change with speed, and I don't believe it's laminar flow at high speeds.

Just an experiment, if it's not too dear in time and trouble, take the trim tabs off, or raise them out of the way. I don't think they came with the boat, may have been added at an ill advised moment, may be ill adjusted, and may be the entire source of the difficulty.

[ 07-14-2004, 02:01 AM: Message edited by: Jack Heinlen ]

[Meerkat]

If the boat had one side always facing the sun while it was hauled out, wouldn't it dry that side more and make it more buoyant? Maybe warp it?

[Victor]

If it leans at rest AND underway there must be hull distortion. Perhaps the port side is somehow distended ever so slightly.

[htom]

There are (at least) two or three things going on. Static balance is one, does she rest evenly in the water when at rest? Another, harder to determine, is what I'll "shape balance" because I can't remember the fancy name, is whether the hull and the appendages are balanced and aligned (no tilt to rudder when it's over, etc?) The third, dynamic balance, is how she balances in motion; things like prop and engine torques get added to the previous balance.

I'd get out a tape and measure from chine to the center of the rudder on each side, for example, and to the center of any struts and the prop.

[tcmers]

Got the boat back out this weekend. After lauch, we tied off at the dock, and got out of the boat to see what it looked like without passengers. With all of our normal gear, plus 75 lbs. or so of additional stuff, it sat pretty evenly at rest. So far, so good. Two of us got in the boat, and moved around to see what effect we had. Obviously, both of us on one side made a difference, but overall, still good. Before going out, we took off the spring loaded, psuedo trim tabs as Jack suggested. Installed a set of Lenco electric tabs, but apparantly got a bad switch, so they have to go back. Looks like Jack wins the prize. With the old tabs removed, we had a very level ride. Can't believe they would make that much difference. Didn't push it, stayed in the 15 mph and under range most of the day. Was pretty windy and choppy at times, and lot's of water skiers out making rather large wakes. Had no issues in any of that. All in all a great day on the water, and a great relief to realize we didn't have a huge problem with the hull. Thanks for all of the input. The people on this board are great.

[imported_Dutch]

Yeah! Ish! [img]smile.gif[/img]

[Victor]

Must've been just a coincidence then that the weight distribution made it list to the right and so did the tabs. Glad it worked out. How bout a picture?

[tcmers]

Victor, we have a couple of pics, although the pics of her on the water haven't been developed yet. (left the digital camera home) Tried posting a couple pics in another thread, and couldn't get it to work. We'll get some posted if we figure it out.
We agree that it was coincidence that the weight distribution (although we dind't move much) and tabs were working in the same direction. It looks like under 20 we'll have a very stable ride, which is faster than we want to go anyway. We played with it quite a bit today, taking other boats wake from every direction, turning hard under power, etc. Everything was great. It may be that the at rest problem wasn't as bad as we percieved on our initial ride, and the tabs were the issue under power. Anyway, today life is good!

[Jack Heinlen]

If the boat rides well without them, I'd leave them off, at least until you've become more familiar with the ride characteristics.

The hull forms of these ply-planked 'sea skiffs' went through a gradual evolution. Starting in the late forties(earlier if you count the solid-wood planked boats) with boats that had the beginnings of a broad planing surface aft, like the Lyman Islander, that surface gradually increased to accomadate larger and more powerful engines. By the middle sixties the final form was reached. It had increased flair forward and a broader, very flat run aft with hard turns at the bilge. This made for a very fast and dry hull with the larger motors, but has always looked slab sided and clunky to my eye, which grew up with the more rounded forms designed for less power.

It would be interesting to see the lines of your Skiff Craft. A four cylinder in a boat this size was not the norm, for the later Chris' and Lymans in anycase. Look at the ads for them, and you'll almost invariably find a small block V-eight. Way too much power, no small part in response to the increasing inroads of 'glass construction. And gas was cheap!

You've got a very well made boat, built by Mennonite and 'modern' Amish craftsmen, out of some of the last old-growth doug fir ply. They may have switched to mahogany in there somewhere.

I'm glad my suggestion helped. It's nice to be right once or twice a year. [img]smile.gif[/img]

Have fun. It sounds like a fun little boat.