170 Montauk on Hoist

A conversation among Whalers
tonymc
Posts: 6
Joined: Wed Apr 07, 2021 4:42 pm

170 Montauk on Hoist

Postby tonymc » Wed Apr 07, 2021 5:03 pm

I recently purchased a 2013 MONTAUK 170. I was planning to keep the 170 MONTAUK in my boathouse this summer and not tied to my dock. My boathouse has a hoist system. I prefer to not tie the boat up on the dock and not leave it in the water in the boathouse.

I was not thinking twice about using the bow eye and the two stern eyes to hoist the boat, but I received feedback from Boston Whaler (and read in the owner's manual) that those eyes are to be used only for short-term lifting.

Q1: As used by Boston Whaler what does "short term" mean?

Q2: To any reader who has employed a hoist system as I described: were there problems?

--Tony

User avatar
Phil T
Posts: 2602
Joined: Thu Oct 22, 2015 6:08 pm
Location: Was Maine. Temporarily Kentucky

Re: 170 Montauk on Hoist

Postby Phil T » Wed Apr 07, 2021 9:55 pm

Here are the pages from the manual.
Screen Shot 2021-04-07 at 9.31.50 PM.jpeg
Screen Shot 2021-04-07 at 9.31.50 PM.jpeg (85.21 KiB) Viewed 6243 times


Personally I would lift the boat with wire cables then position wide lifting straps slightly forward of the transom and a second aft of the bow and support the hull that way.

The straps would be set at a fixed height and the wire rope would be for lifting and lowering only. All weight would be on the straps.

For storage for a few days, use the eyes.

Once you figure out the rigging, it should not be hard.

Here is a rough drawing.

strap2.jpeg
strap2.jpeg (23.67 KiB) Viewed 6243 times
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

jimh
Posts: 11672
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: 170 Montauk on Hoist

Postby jimh » Thu Apr 08, 2021 7:12 am

With regard to the exact duration of a period of time described as "short-term", I would ask Boston Whaler for a specification. To me, short-term means an hour.

What Boston Whaler is clearly saying: don't hoist the 170 MONTAUK by the bow and stern eyes and let it hang that way for days or weeks or months. They must have some basis for giving that advice.

Whether some other 170 MONTAUK owner attests that they could hoists their boat in a manner contrary to Boston Whaler's advice does not seem particularly dispositive that it can be done with no harm.

Another solution: lift the boat with the bow and stern eyes as you planned. Then position two cross member timbers under the hull and lower the hull onto to them. That might be awkward, but perhaps it would be a better method for long-term out-of-the-water storage.

The notion of hoisting a Boston Whaler by the bow and stern eyes was probably more workable with the 13 and 15-foot hulls. The weight of those hulls was much less than a modern 170 MONTAUK. The strength of the bow and stern eyes and the points where they are attached was then the same as now--but the 170 MONTAUK is much heavier.

Also, I would be wary of a lift using a single point of lift. Such a lift creates a compressive force on the hull.

MarkCz
Posts: 131
Joined: Sat Jan 27, 2018 3:44 pm

Re: 170 Montauk on Hoist

Postby MarkCz » Thu Apr 08, 2021 11:38 am

Does your boathouse hoist system have a single hoist with one attachment point?

tonymc
Posts: 6
Joined: Wed Apr 07, 2021 4:42 pm

Re: 170 Montauk on Hoist

Postby tonymc » Thu Apr 08, 2021 7:04 pm

Hi folks, thank you for the responses.

Boston Whaler directly didn't specify what the short term was. Actually, I couldn't reach them myself and had to rely on a dealer to give me more feedback than what was in the manual. The dealer's opinion was Boston Whaler didn't want to say anything other than what was in the manual because of liability.

The use case for me would be the boat would hang in the boathouse and I may or may not use it daily or even weekly however I would use it more than four times a month.

It didn't even occur to me that [hoisting a 170 MONTAUK by the bow eye and stern eyes] would be [advised against] because I have a 20' Malibu ski boat and a 24' Natique ski boat I would hoist regularly for short periods and long periods. So I decided to come to this forum to see if there was any experience good or bad.

I decided to draw what the boathouse looks like since you all had some great ideas on how to add additional support.

[Changed topic to discuss how to upload images and make them in-line. Please visit the INTRODUCTION FORUM and read the article on adding images files to a post and maximum image size. The GAM forum is for boating topics. The INTRODUCTION forum is for help with using the forum software.--Moderator]

The width of the internal boat house prohibits me from sticking boards underneath because they would need to be more than 20' long. The boathouse is one big slip. It would also be hard for me to add additional wide straps to wrap underneath for extra support unless I got into the water or used a hook to grab one end of it from one side of the boat to the other. Nothing is impossible however doing these two suggestions would be something I wouldn't want to do.

The other alternative is to use the straps from each hoist to secure the boat from hitting the sides of the boathouse but then I would leave it in the water.

Thank you again.

tonymc
Posts: 6
Joined: Wed Apr 07, 2021 4:42 pm

Re: 170 Montauk on Hoist

Postby tonymc » Thu Apr 08, 2021 7:16 pm

dwg_a.jpg
Fig. 1.
dwg_a.jpg (102.37 KiB) Viewed 6103 times

tonymc
Posts: 6
Joined: Wed Apr 07, 2021 4:42 pm

Re: 170 Montauk on Hoist

Postby tonymc » Thu Apr 08, 2021 7:18 pm

dwg1a.jpg
Fig. 2. Hoist strap detail.
dwg1a.jpg (23.97 KiB) Viewed 6103 times

User avatar
Phil T
Posts: 2602
Joined: Thu Oct 22, 2015 6:08 pm
Location: Was Maine. Temporarily Kentucky

Re: 170 Montauk on Hoist

Postby Phil T » Thu Apr 08, 2021 8:23 pm

Tony--my suggestion comes from watching the RNLI in the UK. They retrieve their Severn/Trent class rescue boats (14'm LOA, 28 tonne) by winching them up a long steep ramp via cable, then change to an industrial strap harness for the distance into a boat house. The strap is what keeps them secure.
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

tonymc
Posts: 6
Joined: Wed Apr 07, 2021 4:42 pm

Re: 170 Montauk on Hoist

Postby tonymc » Thu Apr 08, 2021 8:55 pm

Thanks Phil. My hoists are rated at 2-tons each they have a chain with a loop at the end which I then connect industrial straps to each hoist independently then to the boat eyes. The straps are nylon and rated for 4-tons each. My concern is more about the potential of damaging my new 170 MONTAUK rather than keeping secure. With the boat in the boathouse, it would be very protected and secure.

jimh
Posts: 11672
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: 170 Montauk on Hoist

Postby jimh » Fri Apr 09, 2021 10:24 am

What is the dimension for the distance between the I-beams the support the hoists in Figure 1?

Is the location of the hoists on the beam supports fixed or moveable?

From Figure 1 I infer the boathouse is open to the sea on the right.

[Note: I reoriented the image files in Figure 1 and 2 to make the text upright when viewed as in-line files in HTML.]

jimh
Posts: 11672
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: 170 Montauk on Hoist

Postby jimh » Fri Apr 09, 2021 10:58 am

In order to create the least stress on the attachment points on the boat for hoisting, the direction of the lifting force should be completely vertical, that is, the hoist rope (or chain or strap) should be hanging down perfectly vertically when connected to each eye. In this way there won't be any lateral forces created on the lifting eyes; the load will just be vertical. Any change from a perfectly vertical lifting rope will create compressive or elongation forces on the attachment points (the eyes) and then transmit those forces to the hull.

If all the hoists and support beams are fixed in place and cannot be moved to fit the boat's lifting eye layout, the most effective way to move the lifting points so they align with the eyes on the boat is to make a frame--usually called a strong back frame. The lifting straps to the boat attach to the strong back so they pull up perfectly vertically, while the chains from the hoists attach to the strong back where needed. Considering the total weight of a 170 MONTAUK to be lifted, the strong back frame could probably be made from timber to save money, or to save weight from aluminum.

If designed with an eye to creating room for the center console windshield, the strong back frame could end up positioned rather close to the boat, that is, the strong back would not have to be kept entirely clear of the console windshield; the windshield and console would fit into an opening of the strong back frame.

With this method, the lifting forces would be kept to just the vertical direction, and no sideways forces would be exerted on the lifting eyes or their surrounding hull structure.

jimh
Posts: 11672
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: 170 Montauk on Hoist

Postby jimh » Fri Apr 09, 2021 11:05 am

Regarding why Boston Whaler explicitly cautions against lifting the 170 MONTAUK by its lifting eyes for "long term", it has been suggested that this is due to concern about exposing Boston Whaler to risk of being "liable" for some future harm.

I think the risk is clearly laid out in the cautionary statement in the owner's manual: what is at risk is the occurence of "stress on the fiberglass and gel coat." And the risk is that such outcomes "can occur."

These are really rather mild terms. The advice is just cautionary. The risk is something than "can occur." They don't explicitly prohibit the practice. And they further obscure the basis for the occurrence by limiting it to "long-term" practice.

The boat under discussion is a 2013 model, possibly made in 2012, so its ten-year hull warranty is going to expire in a year or two.

I'd try lifting the boat using the eyes with the strongback frame I described above, and then carefully watch for any indication of harm to the gel coat and fiberglass of the hull around the lifting eyes. If a big crack develops after one week, then you have the answer to how long a "long-term" use was.

User avatar
Phil T
Posts: 2602
Joined: Thu Oct 22, 2015 6:08 pm
Location: Was Maine. Temporarily Kentucky

Re: 170 Montauk on Hoist

Postby Phil T » Fri Apr 09, 2021 1:31 pm

Instead of a two step hoist I described above, consider going with a spreader bar type setup.

From each hoist would be two straps/wire cable to a spreader bar the legnth necessary to span the beam of the boat.

From the each spreader bar a strap (with small weights) would fall from the end, down and around and back up.

One would enter the boat house with the straps in the water ~1ft. On reaching a location where the straps were lined up with pre-set marks on the gunwale, the hoists would raise the boat.

Given the boat only needs to be lifted a 1-2 feet off the water, if a strap did fail, it would not be catastrophic.

Horrible drawing not to scale:

Montauk_lifting_strap_hoist.jpeg
Drawing
Montauk_lifting_strap_hoist.jpeg (37.89 KiB) Viewed 6076 times
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

tonymc
Posts: 6
Joined: Wed Apr 07, 2021 4:42 pm

Re: 170 Montauk on Hoist

Postby tonymc » Sun Apr 11, 2021 1:35 pm

JIMH--I think the distance between the two I-beams the hoists are at least 10-feet. The width of the whole bay accommodates two boats to fit into the boathouse. The I-beams are rated at more than 15-tons. The hoists are connected to the lower portion of the beam and operate on wheels, and in that way they automatically adjust to the size of the boat, always creating vertical lift and reducing stress. The boathouse is on a large inland lake. There is a vinyl door that rolls up and down to protect the boats from any outdoor weather. Thank you for adjusting the images.

PHIL T--the spreader bar is a good idea; we used that for a jet ski connected to a cradle. I will have to look at that more closely to see if we have the height in the boathouse so that it didn't hit the center council. For our jet ski, the spreader bar was always in the way of our heads.

padrefigure
Posts: 91
Joined: Sun Oct 18, 2015 9:26 pm
Location: Texas, Hill Country

Re: 170 Montauk on Hoist

Postby padrefigure » Fri May 28, 2021 9:51 am

Why not make a cradle from I-Beams and rails, lower into the water, drive the boat onto the cradle, lift out of the water using the winches?