Boat Lifts with Stepped Hulls
 

Maybe there is a thread out here on this topic, but I did not find it. I have a Donzi 27ZR with stepped hull (2 steps). I am thinking about purchasing a boat lift. Probably a Shorestation. My question relates to the bunks on the lift. On my boat trailer, the bunks are stepped to match the hull. This way no weight is being put at the point of the steps. I would assume that I would have to have a similar setup on my lift.

I called my Shorestation dealer here, and he had asked Shorestation corporate about this issue before, and they didn't really match the bunks with the hull steps. They simply set up the bunks on the lift so that they angle up towards the back of the boat, so the boat sits level once hoisted (in other words, the bunks on the lift are straight, and not stepped to match the hull). This would seem to me to not be the ideal set up. Seems to me that there might be too much weight on the point of the steps, which I wouldn't think is good for the hull.

Any thoughts on this?

Rick

I was worried about that too. So, I took all the measurements and put the steps in my bunks on my lift. Just to ease my mind. Not sure if it effects the hull but i would think it does if its out there all season or longer.

My .02c

From a pure engineering standpoint, matching the bunks on the lift to the hull is very desireable so as to evenly distribute the force / weight. This is important not only for the hull, but the bunks as well.

Just remember that you will have more of a "one way ratchet" effect on the lift where the boat will not want to back out - because of the steps - until the bunks are fully clear. You occasionlly see this on trailers in a shallow launch, but the trailer is angled. Your lift bunks will be horizontal.

I assume for a 27' Donzi or any other smaller lift, like ours. You will have (2) mainframe members that your bunks bolt to. If the shorestation lift bunks is built anything like the hydrohoist or boatfloaters - they just flex and bend with the boats bottom (not step) contour. Most of the boats weight is carried right at the bunk mount to the mainframe area.

Unless you have a step within a foot..., foot and a half, from the bunk mounting point - i wouldn't sweat it.

Absolutey cut or add to your bunks to make it match your step bottom. If your lift manufacturer won't do it, they are lazy.

You run the risk of chipping the edge of your steps due to the weight stress, or worse, deforming the hull over time.

The bunks on your lift should be narrow enough not to hit your steps. My sunstream lift bunks are only 30" apart.

I have a 35ZR on a ploy lift ay LOTO
I called the factory, got a drawing from them used to set up trailers.
The drawing gave exact mesurments for the size of the steps.
Got some pressure treated lumber.
Had a buddy with a plainer cut them down to the proper thickness.
Mount to rails, new carpet on bunks.
Problem solved, perfect fit.

Sorry, but this is common sense, and shorestation has none apperantly. Your boat doesn't know if it's sitting on a trailer or lift. It does know if it's sitting on an edge. Match the bunks to your boat, as your trailer is.

Mine just took an extra 2x4 on top of the lift bunks to match the step height. They do not have to be the full length of the steps. Keeo them a little short towards front so the boat has a little room to move w/o catching the edge of your step as it raises or lowers. Mine start a approx 12" back from step.

Um, my boat lift is not pulled behind my truck at 60 mph around corners and over bumps. A lot of us have our boats on lifts without custom bunks. Just enjoy. Common sense??

Do you like the bottom of your boat the way it is??? Proper support is critical.. your money..

Bunks
 

[QUOTE=tomahdonzi;3656174]Maybe there is a thread out here on this topic, but I did not find it. I have a Donzi 27ZR with stepped hull (2 steps). I am thinking about purchasing a boat lift. Probably a Shorestation. My question relates to the bunks on the lift. On my boat trailer, the bunks are stepped to match the hull. This way no weight is being put at the point of the steps. I would assume that I would have to have a similar setup on my lift.

Any thoughts on this?

You could speak to your trailer manufacturer. Example, MYCO, who made my trailer, would fabricate a deck for your lift matching your hull just like the trailer.

Fearless010
Peter

Your boat still weighs the same no matter what it is sitting on. Now if you want to put that weight on the edge of your step, go right ahead. Or you can evenly support the hull. Thats the common sense. There's a boat on a lift down from me that is sitting on an edge that the hull is pushed up a good inch. I'll grab a pic this weekend. But it's not my boat. So I could care less

Your boat will shape to what ever it is sitting on. Fit Your bunks to Your boat.............

This is the problem I have with storing at a high and dry, just two straight boards

Boat Lift with Stepped Hulls
 

Guys,

Thanks for the comments. I agree that I should match up the bunks with the steps on the boat, just like I do with the trailer. These big lifts now use aluminum bunks with carpeted wood bolted to them. So on the big lifts, I don't think you will see any flex in the bunks, and thus putting a fair amount of pressure on the steps, which I don't think is a good idea. I like the idea of just adding some carpeted wood as we move toward the back of the bunks, to match up to the hull (and I agree that you have to be careful to get the lift down enough so the front hull does not hit those higher bunks in the back). I also like the idea of maybe moving the bunks in quite a bit so they miss the steps. That's something worth looking at too.

Thanks again. I have the engineers at Shorestation looking into this as well. Will be interesting to see what they say.

Myco does manufacture and sell racks that fit the bottom of your boat for use on a lift.

you can also cut the steps into the bunks to match the bottom of your boat like we did, see pics. pics are before we added carpeting obviously.

ktron,

Thanks for the myco info. That looks like the way to go. Now I'll just have to look a little closer at the proper Shorestation lift to see how they mount the bunks (they use aluminum bunks with wood over them, so maybe we just eliminate the aluminum and go with this set up).

Thanks.

We have a slip available for the 2012 Summer Season that includes a boat lift. The lift will accommodate a boat up to 29' for $100/ft~!!
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All the decent lift makers at LOTO place extra boards in to fit the steps. They leave about 6-8 inches of play when sizing the boards so that you have a little leeway on exactly where your boat sits on the bunks, and it will still give proper support. Also make sure your lift drops low enough that your steps clear the extra boards when backing off so the boat doesn't get hung up. At LOTO they set depth with chains so you just need to lower the chains a couple links.

Depends if the lift is a back in model or not. If back in, not a problem.

That's because they already have the lift lowered enough that your drives will clear which leaves plenty for your steps.

The other thing they did when they set mine up for steps is they cut the front facing angle of the added boards at an angle - that way if your steps ever did get hung up backing off, they wouldn't hit at a 90 degree angle and the steps could slide up the angle.

As others have stated, it just makes sense to properly support the hull with the bunks. No reason not to as it is very easy to simply add to the main bunk sections for the hull to rest on.

Pics are showing modified bunks for my twin stepped Formula 292 which should be similar to your Donzi 27ZR. Through bolted to the main bunks are 1X4's in the middle and 2X4's in the back. When on the lift the hull forward the steps rest on the main bunks, between the steps on the 1X4's and behind the steps on the 2X4's. The boat pulls in forward and I make sure the rear of the bunks extends past the transom. This prevent the bunks from forming a hook in the bottom of the hull over time. This lift drops down plenty far for the steps to clear these pads when backing out.

Just use galvanized carriage bolts. Counter sink the holes in the wood and cover with carpet. Very easy install. Good luck!

This is a boat on an incorrectly setup on a lift.
10min of someones time and this would never be an issue. Didn't get a good pic from the other side of hull, but it also has the AC pickup scoop positioned right on top of the bunk. The hull is deflected a huge amount from that. That location is approx mid point between the bunk mounts, so the bunks to spread out the weight at a pretty fair amount, not just over the mounting location.

This boat has been on this lift 2 seasons now. This pic was taken yesterday, the deformation was apparent within the 1st season.

ouch that looks bad:(





I just added a 2x4 to the top of mine and cut it down to match the bottom,

strip what is going on with that first pic i see no water.

I set the camera on the pier for a diff angle,my lift will lift it almost 2 feet above the pier.That way I can use the barge in the pick and buff on the bottom of the boat:drink:

Rob

Hey thanks for the ladder again,Working great

Rick you definitely want to properly support the individual steps on your hull. A straight bunk on you boat lift could do damage to the steps, and/or (over time) warp the hull of the boat.

I ran into the same situation just recently with my boat. I have a 20,000 US Boat lift and ordered it without the standard straight bunk. Instead, I had a custom cradle made by Myco in Florida (yes, the same company that makes the Myco Trailers). Their cradles aren't cheap, but they are first class and the finished product matched my hull perfectly. I attached a picture of the cradle Myco built for my Fountain 38EC. Check on their website for additional pictures of their lift cradles.

If you don't want to spring for a custom made boat lift cradle, I recommend at least building your own stepped bunks out of wood, and cover them in good carpet (even the step rise areas).

Oh, one other tip about stepped hull boats. When you launch your boat be 100% sure the boat is completely floating clear of the stepped bunks on your trailer. If not, when you go to pull your trailer out of the water the stepped bunks can snag on the forward step of your hull and can cause fiberglass damage.

That Myco is beautiful. One day I will have one with the platform at the rear so I can clean the transom while its on the lift.

Very nice Myco cradle. Definately the ticket. I am likely looking at Hewitt Hydraulic lift here in Wisconsin in the next couple weeks. The local dealer seems to have a better handle on stepped hull issues than ShoreStation.

They also offer a cradle setup, probably not unlike Myco. Will look at that option, or for sure build up the bunks to accomodate the steps.

One thing I need to think about. Do I go with Wood bunks with carpet set on top of aluminum bunks (and simply add more carpeted wood where necessary), or go with the option aluminum bunks (with a rubber pad above an aluminum bunk). Guess I'm wondering how durable wood is. Certainly easier adding wood to wood (and cheaper ) than adding wood to aluminum or adding aluminum to aluminum.

What are the bunks on the Myco cradle? Wood?

How did Myco get the correct fit? Did you have to give them some measurements, or do they just know the dimensions of various boat hulls?

Rick

They have mesurements on most hulls,like my Hustler they were giving mesurements from Hustler,then they make a cad to build the trailer.

Rick - Once I provided Myco with the serial number of my hull they knew the exact dimensions of my Fountain's hull and emailed me a detailed drawing of what my cradle was going to look like. Myco has been building trailers for Fountains for years. To get to this level of design detail for their cradles and trailers the Fountain factory must have shared a lot of data with Myco. Myco is even aware of what changes were made to the Fountain hull's from serial number to serial number (within the same model).

I think the bunks on my Myco cradles are wood covered in carpet.

SR-71

I agree that you should support the bottom the same way it is supported on the trailer, and that is what I would do if this was my boat.

But, one thing I have not heard here yet is what does Donzi say. The first thing I would do is ask the manufacture of the boat how it should be supported. I'm pretty sure they will say same as trailer. I also would think they would happy to give you the measurements needed to make a proper lift support.