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Lifting in keel bolts

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Sjosno View Drop Down
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    Posted: 16 October 2017 at 09:07
Hi there,
Being new to this forum I am hopeful to get some feedback on a thought I have.

As an X-Yacht sailor for many years I always lifted the boat in one of the keel bolts with a lifting strap going through the coach roof in a designated hole.

After becoming a Hanse sailor (445) I have learned to appreciate both the building quality as well as sailing performance of my new boat.
When hauling the boat is lifted "traditionally" with to lifting straps around the hull.

After an accident at my club when a boat was actually dropped back in to the sea, I started to think about the possibility to lift my Hanse in the keel bolts instead. I have the 1,83 draft keel.

My plan was to connect lifting straps to 2 of the bolts. One in front and one in the back of the keel.
The two straps would be led out through the two skylight hatches through the roof creating an angle that would stabilize the boat "front to back". A common problem with center lifting is to balance the boat.
With a two strap construction it would not only be stronger but also much more stable.

The keel bolts should be the absolute strongest thing on the hole boat so I can't really see any structural problems..

I fully aware that center of gravity might not be at all where I expect. I have only done a rough assessment from drawings, location of the keel and hatches..

Have anyone ever tried anything like this? Feedback is much appreciated!
Thanks! David

Edited by Sjosno - 16 October 2017 at 10:07
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High Time View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote High Time Quote  Post ReplyReply Direct Link To This Post Posted: 16 October 2017 at 13:20
Hi David

I'm curious why you think this would be a better way to lift the boat. 

With the traditional method of lifting with the straps around the hull, the straps act rather like the water taking the whole weight of the boat through the hull, with the keel hanging on the keel bolts, similar to the distribution of the stresses when the boat is floating in the water.

With your suggested method the whole weight of the hull and interior plus some of the deck and fittings would be concentrated on the width of the keel, in the opposite direction. (I accept that some of the weight of the mast and deck will be taken directly through the mast compression post). This is similar to the stress pattern when the boat is ashore sat on its keel in the yard, except that some of the hull weight is then taken by 6 or more props on the hull.

A further concern when lifting by the keel bolts is sideways stability. If the CoG is above the lifting points (quite possible given that the keel is only 30% of the total weight), there will be tendency for the boat to roll over.


Edited by High Time - 16 October 2017 at 13:22
Roger

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Sjosno View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sjosno Quote  Post ReplyReply Direct Link To This Post Posted: 16 October 2017 at 17:10
Hi Roger,
Thanks for your feedback!
My experience from center lifting is really good, as being a safe, problem free and gentle way to lift the boat.
No risk of straps skidding on the hull, log, transducer and s-drives are out of the equation.
In my case it would also allow me to use the "club crane" as this, although having the lift capacity, is not tall enough to lift the boat sufficiently to get my trailer underneath the boat if spreaders are in place.

The boat is designed to stand on it's keel when on land. The supports are only ther from stop it from tipping over.
My boat sits like this 6 months per year.. I can't imagine there being a structual problem to lift in the keel.
That said I'm not an expert in keel bolts and how structual rigid they are on a Hanse 445.
Regarding CoG you are absolutly correct If unstable the strap will end up in one of sides of the skylight hole, putting the full load of keeping the boat upright there. So more info is needed
I hope someone in this forum might know more..
/David

Edited by Sjosno - 16 October 2017 at 17:15
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Rubato View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Rubato Quote  Post ReplyReply Direct Link To This Post Posted: 16 October 2017 at 17:30
If I were considering this myself, I would be contacting Hanse and only following their advice.

Good luck
Steve

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Post Options Post Options   Thanks (1) Thanks(1)   Quote Peter-Blake Quote  Post ReplyReply Direct Link To This Post Posted: 16 October 2017 at 19:06
I would not consider this way of lifting my boat.
In older days with smaller boats it was somehow usual to lift a boat like you would like to do.
My old boat  was able to be lifted with one steelstrap (it had about 50% of its weight in the keel). But any harbourmaster ignored it and used his standart procedure....

The older boats had a lot higher keel weight in %!

The yachts today do only have a keel weight of 30%. So if you would try to lift a boat with only 30% keelweight on the keelbolts, than your boat will flip around, as 70% of the weight are above the fixing point (keelbolt) for the strap. OK a little bit simplified.......but i thing it explains the problem...

the 445 haas a keel weight of about 32%!


Edited by Peter-Blake - 16 October 2017 at 19:07
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Post Options Post Options   Thanks (1) Thanks(1)   Quote StavrosNZ Quote  Post ReplyReply Direct Link To This Post Posted: 16 October 2017 at 21:03
Like the other replies i would not be considering lifting my Hanse by keel only. As stated previously all of the weight of the hull will effectively be sagging on the keel and you are likely to have other issues as a result of putting stresses that the boat was never designed to have on the rest of the structure.

Nor would i even rest my Hanse on its keel only, I have seen to many production boats pop fairing around the keep to hull join as hull sags on the keel. 


Stephen
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samuel View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote samuel Quote  Post ReplyReply Direct Link To This Post Posted: 17 October 2017 at 07:52
If someone was ham fisted enough to drop a yacht using the tried & tested method then I would imagine that they would be just as ham fisted with a non standard method. I would suggest that you use different operators & lift the yacht in the way that the majority of the yards lift them at present. ie with straps correctly spaced & braced. If using a crane then the spreader bars should be correctly braced for the size of the vessel. I certainly would not want to start playing about with keel bolts & brackets etc

I agree, however, that it would not tip over because the holes in the cabin top would stop this & it would be easy to take lines from the chain plates to the lifting line to hold the boat upright. It might still lean a little making chocking awkward.

I would also point out that even my 31ft Hanse sags if not properly supported as can be seen by the floor boards on the cabin lifting 10mm just behind the keel if not properly supported. I would imagine that the 445 would sag every bit as much, so lifting by the keel would place a lot of strain on the hull.


Edited by samuel - 17 October 2017 at 07:59
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Sea-U Quote  Post ReplyReply Direct Link To This Post Posted: 17 October 2017 at 09:57
I would have given it a try.
If you have a crane that only can lift by the keel bolts, it would be silly to order another crane.
I am quite sure the boat will hold.
Sea-U is a 370e #532 located SW Norway
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Sjosno View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sjosno Quote  Post ReplyReply Direct Link To This Post Posted: 17 October 2017 at 13:01



     
     
     
Thanks for valuable input!

A lot of boats are lifted with a center
lift system.
All X-yachts (whatever size), Sweden
Yachts, many of the Norlin constructions etc.
Here is a link to a guy that installed
it himself on his Dehler 34:
In my club boats are lifted by
entrepreneurs and transported 600m to the boat yard for the winter. Heavier boats (+10 tons) need a mobile
crane to do the job. The boat is the lifted on to your trailer, after cleaning, and
pulled away by a truck. The mobile crane part is a bit of a hassle. (and expensive)

The club also has it's own crane. It's
fixed and is used to lift the boats for cleaning.
With a center lift system I could use
this crane to lift the boat, clean it, lower it into my trailer.
It would also be easy lift the boat with
the mast on during the season for whatever reason.
My boat stands on its keel with 8 supports when on land. The absolute majority of weight are on the
keel. The supports are tightened after the boat in place on the
trailer. During winter I loosen and ”re-tighten” the stands a
couple of times to avoid to much pressure on any individual stand/support.   

To have 10mm ”flex” behind the
keel when put into a cradle with side supports would worry me a lot.
I have never experienced any movement what so ever in any boat I've
had. However, I've seen a lot of supports
pressing to hard on the hull creating concave indents on single
laminate hulls, and fractures in form of small cracks on double
laminate with distance material.

The accident I mentioned before was actually the first I have witnessed during my 35 years of yachting.
It haven't deterred me in any
way from lifting with spacer and two slinga.
Wanted to look into the possibility of something I have good experience from with other boats.
If my Hanse can't be lifted with a
center system or if it's unwise I can, and will live with it. :)







Edited by Sjosno - 20 October 2017 at 01:56
David
Pixie 2   Hanse445 #112   loc, W.Sweden
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