18 classic lists / leans to the left...?

[merlin502]

Took my (new to me)1995 18 Classic for its maiden voyage today; I am concerned that the boat lists to the port side, regardless of trim position. I don't have tabs and I realize how sensitive this boat can be with weight distribution. I have my 130lb wife as a passenger and my 90lb daughter in the back seat, and I am only a meager 192lbs.
Everyhing is stock on this boat; 350 mag, 3-blade mirage, alpha drive. but I noticed the drive does not have that little skeg above the propeller, only a flat anode plate w/o the skeg.
If I feather the trim up and down it makes a little difference, but not enough t flatten out the boat. I have owned a few go-fast boats, but never had this issue before. I am still smiling from this incredible day on the water, but am wondering if I need to buy trim tabs, or what?
Thanks in advance for your opinions!
Merlin502

[Donzi Vol]

Merlin,

I've been in a couple 18's that have done that. Luckily in my case we had tabs and could fairly easily correct the problem. Hopefully the other guys will have a simpler solution, but if you've got some spare cash, I'd invest in some tabs.

One question, what happens once you give her a little more throttle? Does it still lean after you get to a plane?

[Mr X]

Sounds like you have a hook on one side or a rocker on the other.
You need to get the boat up in the air and check the bottom with a straight edge. Was the boat sitting on a roller trailer or possibly hanging from davits
for a while?

[The Hedgehog]

What speed is this happening?

Mr X is right, check for hook.

[Donzi Vol]

See, I told you these guys would know what to do. Sadly my solution to a problem is to just spend more money. And I digress

[Carl C]

This condition is normal on a lot of 22s and I don't see why the 18 would be much different. I run a little port tab always except on high speed runs where the increased trim compensates for the prop torque and I can ease the tab up. Then I must lower the tab and drive when slowing down. These boats do not have a pad bottom and are balancing on a small section of round keel, therefore they sometimes list in reaction to the prop torque. Check the bottom with a straight edge as suggested but I suspect you'll be in the market for a set of trim tabs.

[merlin502]

Thanks guys. I just put a 4 ft' level under the boat. The port side hull is straight as an arrow and the starboard side has a slight hook. Maybe a 1/8" to 1/4" gap about a foot from the transom. The strakes both have a gradual hook, but it appears that they are similar. This boat has always been on a bunk trailer (as far as I know), so I am guessing this might be a factory flaw...
I have not had the boat aired out on choppy water yet. My guess is that the smooth water I was on yesterday only exagerates the effect of that slight hook.
I think I will price out some trim tabs...

[Sam]

Torque ! would be my first guess. It happens with my sixteen, just touch the tab and it disappears.

[mjw930]

Thanks guys. I just put a 4 ft' level under the boat. The port side hull is straight as an arrow and the starboard side has a slight hook. Maybe a 1/8" to 1'4" gap about a foot from the transom. The strakes both have a gradual hook, but it appears that they are similar. This boat has always been on a bunk trailer (as far as I know), so I am guessing this might be a factory flaw...
I have not had the boat aired out on choppy water yet. My guess is that the smooth water I was on yesterday only exagerates the effect of that slight hook.
I think I will price out some trim tabs...

Hmm, hook on the starboard side, lists to port underway. Sounds like you found your problem. 1/4" hook is huge, you should have a glass guy take a look and get it cleaned up. In the grand scheme of things it won't be that expensive. With that much hook tabs aren't going to make you happy.

[Mr X]

1/4 inch hook is huge, that is the problem.
18's have no inherent list from torque, lack of trim tabs, or anything else.

[Mr X]

just read MJW's post above mine........ yup! :yes:
must have been tyoping at the same time!! :wink:

[Carl C]

Merlin502, Mr. X knows what he is talking about. (not that others don't)

[BigGrizzly]

Do not remove those hooks!!! f you do it will porpoise like Flipper. Your problem is the same as every new Donzi guy has. First you need more trim, a lot more trim. the new style anode being flat is fine, the tab on will correct a very small amount of list at slow speeds. The other thing is the prop, I am not in any way trying to start a prop discussion. It is just that some perform better then others with different props.

[merlin502]

Hmm, hook on the starboard side, lists to port underway. Sounds like you found your problem. 1/4" hook is huge, you should have a glass guy take a look and get it cleaned up. In the grand scheme of things it won't be that expensive. With that much hook tabs aren't going to make you happy.


I was just thinking the same thing... Tabs might just be a band-aid for this issue.

You guys that have similar issues with your boats listing to one side; check your hull with a straight edge too. I am curious to know if I am an isolated case, or if this is fairly common on classics.

[merlin502]

Do not remove those hooks!!! f you do it will porpoise like Flipper. Your problem is the same as every new Donzi guy has. First you need more trim, a lot more trim. the new style anode being flat is fine, the tab on will correct a very small amount of list at slow speeds. The other thing is the prop, I am not in any way trying to start a prop discussion. It is just that some perform better then others with different props.

Big Grizzly. Agreed. I would not remove the hooks from my strakes. The starbourd side of the hull, however seems to have a slight hook (concave) over a 4' foot length. I am considering having a fiberglass guy level this out (fill in that 1/4"on the starboard side) so both sides are completely flat. The strakes remain as they are. I believe the hook in the strakes is what helps prevent porpoising, not the actual hull.

[Mr X]

Merlin, you are exactly correct!
Your 18 has the same prop on it that all 18's have had, shipped from the factory for the last 15 years. That is not the problem. A 4 foot hook that is 1/4 inch deep is the problem!

[mjw930]

Do not remove those hooks!!! f you do it will porpoise like Flipper. Your problem is the same as every new Donzi guy has. First you need more trim, a lot more trim. the new style anode being flat is fine, the tab on will correct a very small amount of list at slow speeds. The other thing is the prop, I am not in any way trying to start a prop discussion. It is just that some perform better then others with different props.

I'm confused, he has hook in one side and none in the other so something isn't correct. He may have to add hook to the port side to compensate but it should be balanced, don't you agree? I don't think a prop and trim are going to solve a listing problem caused by hook on only one side of his hull.

I've heard "these specific hulls have hook and these specific hulls have rocker" but does anyone have the exact details for those who might want to blueprint their hull (i.e. depth, length, etc.)?

[BigGrizzly]

Do not remove that and do not level it. I have been there and done that on a 16, a really bad move. The problem isn't the boat it is driving style. at WFO those are not even in the water. The best solution is tabs. I don't use mine on either boat except when tubing.

[merlin502]

Okay. Here is the deal. I crawled under the boat with my straight edge. The chines (inside the bunks, near the bottom of the hull) have equal rocker. The strakes (outside the bunks; center of the hull) both have a slight hook towards the transom. The hook on the starboard side is slightly deeper than the hook on the port side; by maybe a 1/8" at most. There is also a hook on the hull between the chine and the strake (I hope my termonology is correct...) The hook on the hull is also about an 1/8" more on the Starboard side. It is hard to believe that this small amount could make such a difference, but it is such a small boat.
The listing occurs even before I get on plane, but is most noticeable at lower speeds. At 40-50 mph the listing is almost gone, especially if I trim it out. Granted, again; I was on smooth water. I realize this boat is going to trim out nicley on 1-2 footers at full throttle. I also realize the hull's strakes/chines are less in play at higher speeds on choppy water.
I am likely going to add trim tabs to compensate for the listing. Plus, I'm guessing the tabs will make the boat more stable in rougher conditions. I really don't want to mess with changing the hook/rocker on the hull...
Thanks for all your input!

[Mr X]

OH! Then that is different.
then don't change it at all! Griz is right.
The 18 likes tabs mounted on the transom....even in the static position they help.
Not in the water when running it at speed.

Good call Poodle.

[Donziweasel]

Hmmmm.....I was always told the 18 did not really need tabs and that it was never designed with a hook like the 16. I guess my question is, how did he get a hook on both sides and one being an 1/8 deeper than the other one? I know a roller trailer can do some wierd stuff to a hull over time if the boat sits on it for extended periods of time, but he said he had a bunk trailer. I am just curious. I would agree that if he does have a hook in both sides, one deeper than the other, and a lean, tabs would be the easiest and best solution.

[ky-donzi]

Merlin

I have had the exact same issue with my boat over the weekend. I have a 98.. 350 mag, mirage 3 blade 25p prop. the only difference is that I have trim tabs.

When I left out saturday morning the bost listed really bad, proposed alot too. I attributed this all to the supercharger that I have added over winter, more torque wind-up. I tried to correct with my TRIM TABS, but no charge. I found out later that the tabs switches were only working in the raise position. I guess that over winter the switches must have corrided. So I cleaned the switched and.... No more list.

So my opinion is that tabs help tremendouly on a 18 like your. There is no compareison.... porpoising, listing, uncontrollable.... then just a little tab added smooth, level ride..... They make a huge difference

[Formula Jr]

This discussion does beg a question though.

Assume a perfect 18 hull, and a perfectly aligned outdrive and equal weight distribution on the port and starboard sides. Further assume that the boat is always traveling in a perfectly straight line. What normally compensates for the inherent torque, portside, listing reaction of a clockwise spinning prop? There has to be some counter force involved. There has to be some small tweak, some small difference in the mirror image of the port side of the keel and the starboard side of the keel. In all the years of reading this board, no one has ever pinpointed what this compensating force is and how its accomplished on boats that seem to run absolutely even, without list, at speed with out trim tabs.

[MOP]

This all sounds a bit odd, I have a teal 18's close by which I was considering buying. I checked that bottom quite closely with a straight edge the panels were flat not concave, I have always been under the assumption that the 16 was the only hull to have a built in hook. Somewhere along the way I was told the hook on the 16 was put in the hull in the early weaker powered ones, I have been curious why it was never removed with the bigger power options of today. I turned the teal 18 down it had a few to many problems for me, someone else is doing it over.

Phil

[BigGrizzly]

There is nothing wrong with that boat, trim it! Next all single engine boats but cats list. Since your new and looking for a problem. we went through this with fast trucker many dollars later no change to a point. Just drive it and learn to drive it and have fun.

[MDonziM]

MOP - Not to hi jack the thread but if your looking for an 18 there is one near by me in Bayville/ Oyster Bay area. Only saw it only once but the owner moved out West and wants to sell. 71' I think light blue, 350, Volvo. If your interested I can put you in touch w/ the owner.

[Planetwarmer]

WHAT EVER YOU DO, DONT TELL YOUR WIFE TO LOOSE WEIGHT! This may be cheaper now, but in the long run, the tabs will be much cheaper!:shocking:

[mjw930]

This discussion does beg a question though.
Assume a perfect 18 hull, and a perfectly aligned outdrive and equal weight distribution on the port and starboard sides. Further assume that the boat is always traveling in a perfectly straight line. What normally compensates for the inherent torque, portside, listing reaction of a clockwise spinning prop? There has to be some counter force involved. There has to be some small tweak, some small difference in the mirror image of the port side of the keel and the starboard side of the keel. In all the years of reading this board, no one has ever pinpointed what this compensating force is and how its accomplished on boats that seem to run absolutely even, without list, at speed with out trim tabs.

The prop torque is compensated by the left hand rotation of the motor. It's a balancing act and on small boats turning big props the prop torque exceeds that engine torque and the boat lists to port.

If you think the boat lists turning a RH prop then slap a LH prop on it and hold on :D

[MOP]

MOP - Not to hi jack the thread but if your looking for an 18 there is one near by me in Bayville/ Oyster Bay area. Only saw it only once but the owner moved out West and wants to sell. 71' I think light blue, 350, Volvo. If your interested I can put you in touch w/ the owner.

I shot you a PM!

[Pismo]

Tell your daughter to sit on the high side...

[BigGrizzly]

MOP the original 16 and 18 had heavy small blocks in them. Our 1966 had a 289 H&M as did most in our neighborhood of Barnigate bay. never saw anything else up there except Formula jrs with straight six in them. The reason was weight and V design.