Boat Lift: an unusual design for a Boston Whaler hull

[jimh]

I came across an unusual design for a boat lift that was supporting a classic OUTRAGE 25 hull.

Fig. 1. An OUTRAGE 25 hull on a boat lift of unusual design, seen in Dunedin, Florida.

boatLiftOutrage25.jpg (103.21 KiB) Viewed 1718 times

When I first observed the boat lift (as illustrated above), I was a bit confused about how it operated. I deduced that the moving portion was the entire planked deck area. The boat's keel rests directly on the deck, and the four posts constrain the boat to the very center of the deck, as well as acting to limit the amount of heel on the boat once it is raised from the water. The lowering mechanism is not seen in the view shown, but I presume it must be electrically operated.

Several aspects of this design are worth some discussion:

• having the boat supported on a fully-planked deck makes access to the boat for boarding or for working on the boat to be very easy;
• the deck planking must not be wood, as the buoyancy of the deck would become a problem once the boat was floated off, or if the decking is wood, there must be a very considerable weight in steel beams involved in the moving part of the lift;
• the keel of the boat bears the entire weight of the boat, which for a Boston Whaler Unibond hull is the best possible configuration;
• the lifting mechanism appears to be hidden below the two outer (white) beams of the lift structure, but the gear is high enough to be completely out of the water when the boat is raised; and,
• access to the lift deck is flush with the dock finger pier, making for very easy boarding; note the apparently fixed boarding step fastened to the deck on the left to aid in getting aboard the boat from the lift deck height.

The boat shown in Figure 1 is a fire-boat, with a red fire monitor pump in the bow (partially seen). It may also be used as a rescue boat. The hull is the classic OUTRAGE 25. The bow stem and forward v-hull are seen very nicely in this unusual view, demonstrating the classic Bob Dougherty hull design. This boat has a steel keel guard installed. I could not see if it continues for the entire length of the keel, but it very well could. Such a long keel guard would be appropriate for use with this lift, and it would also protect the hull if the boat were to be grounded in the shallow waters near shore in the Tampa Bay area.

One drawback to this design: it is supported by six or more large wooden [pilings], and it is thus a rather permanent installation. In my boating area, north of latitude 45-degrees, most boat lifts are removed by October to prevent damage from winter ice. A design similar to the one shown above might be possible if located in a sheltered area along the shore protected from large ice flows from the open water of Lake Michigan.

[jimh]

Another boat lift of similar type as mentioned above was also encountered, but this time the working elements were in view, as seen in Figure 2 below.

Fig. 2. Another permanently-installed boat lift with a partial deck.

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The lift seen above was located on a small inlet off Tampa Bay, just north of Clearwater. This lift reveals its lifting mechanism quite nicely. While there is not a complete deck on the lifting structure, there is a small deck on the Port side of the lift. And the four tall posts are again used for locating and stabilizing the hull as it is raised from the water.

This lift looks like it could handle a rather long boat, but I suspect the boat profile must be rather low. The image was taken from an old fixed height and rather low railroad bridge that crosses this body of water before the outlet into Tampa Bay. Even at low tide, there would not be a great deal of vertical clearance under that bridge.

Also, the use of four independent electrical motors for control of the lifting cables sounds expensive. On the seasonal freshwater lifts I see in northern Michigan, usually only one motor is used, and the lifting cables have a very crafty arrangement so that the wire rope is spooled on and off of only one drum. In the four-motor lift, it appears that only a single-part rig is employed. In the single-motor lifts I have seen, the rigging is done in a manner that appears to result in a four-part lifting mechanical advantage.

[porthole]

When I was researching boat lifts, I saw many pictures of deck lifts like the ones shown above, but almost all were lake boats.

That Boston Whaler OUTRAGE fireboat looks like it is supported in the normal two bunk arrangement, maybe the keel has some weight on the platform but I would think that would add to instability.

Assuming the guide poles are the typical arrangement for boat small lifts, they are just guide poles. A 1.5-inch galvanized pipe with a PVC sleeve, set into a pocket that is clamped or bolted to the cross I-beam. They would do little to support the boat from heeling over. Even when I have the wind setting me pretty good on the guide poles I can still push the poles away from the hull once out of the water if needed.

I have not seen the hardware on a hidden lift like this. It looks very expensive but given it is a local or municipal fire boat I am not surprised.

I don't have much room around my boat so I am limited to a 12-inch-wide aluminum plank for side access.

ASIDE on WORD USAGE: Dolphins: my understanding is a dolphin is a group of pilings, typically three or more, not a single piling. Why did you choose dolphin over piling?

[Phil T]

Link to manufacturer: https://noprofileboatlifts.com/

[jimh]

Phil--thanks identifying the manufacturer of the lift and for the link their website.

[porthole]

The link Phil provided has a video of cable management. Nothing new there, but a very neat way to hide the motors and cable rollers on traditional lifts. The deck lifts are using hydraulic rams pushing/pulling cables and using directional change pulleys. Exactly like some FD aerial ladder trucks. Compact, powerful and obviously hides well.

They do look nice.

[jimh]

If these lift were $28,000 in 2015, they're probably double that now.

I had not considered how much additional water depth would be needed because of the full deck design. That big deck structure must be able to submerge entirely below the boat's keel.

And having four or six big pilings installed is not going to be cheap, either. Also, the pilings are going to fix the location of the lift. Up here in the Great Lakes we have yearly water level variations of several feet. To account for a low water year, I would have to put the lift in water that was always going to be about five or six feet deep at least. That would mean in a high water year the lift would be in 10 -feet of water. And to get into 10-feet of water some years means a very long dock coming out from shore, more than 200-feet. I think this style lift is really only practical if you have confidence in the water level being the same year to year, and you have some deeper water close to shore.

Up here, the shoreline moves every year, and so do the boat lift positions.

I think the reason these lifts are mostly in Florida is because of no-ice, steady Atlantic Ocean water level, not much tide change, and lots of money. I think Tampa Bay, where the lift seen in Figure 1 is located, has a diurnal tide range of less than 3-feet.

[jimh]

The link Phil provided has a video of cable management...

I think you must be referring to a very fuzzy 13-minute presentation on youTube. In that long presentation, there are some details of the crafty design. There is a mention of "hydraulic motors". Jump to this segment to learn about them:

https://youtu.be/LBFZ7a4TrGc?t=448

and more at

https://youtu.be/LBFZ7a4TrGc?t=628

Apparently an electric motor creates the hydraulic pressure to operate the long linear actuators that pull on the wire ropes that perform the lifting.

From this presentation, it appears that gravity provides the downward force. The deck, without the boat, must not be buoyant.

ASIDE: that presentation should be redone. The quality of the images, by today's standards for youTube, are awful. But I think the lift sells itself, and the company does not need to promote it with a better quality presentation. If they have the original high-resolution recording, they ought to re-upload it to youTube.