Mast Compression - Fisher 25

[gavin400]

I viewed a Fisher 25 that appeared to have a slightly concave deck surface at the foot of the mast.

I wasn't able to see the mast support system from inside the cabin - there is no compression post, so I assume there is some form of beam/support in the coachroof.

Does anyone know the mast support set up on these boats? - they are heavily constructed and I would have thought the loads imparted by the rig would be fairly small?

 

[William_H]

I don't know the boat but if you say they are heavily constructed then presumably quite stiff in the wind. All this results in huge mast compression forces. The heavier the boat more stiff it is the more force needed to heel it over. Only when the boat heels are the forces aleviated.
Yes a compression or dip around the base of the mast is a sure sign that the compression system has failed. It is more often a single post from keel to under the mast.
In this simple case if the post is still intact and original length and siting on the keel then we can assume that the material between the under deck and top of deck under the mast base has compressed. It may have had wood or (hopefully not foam or balsa.
If it does not have a single compression post as you suggest then it may rely on a bulkhead or a strong arch of some sort. The bulkhead can be adequate if thick enough but may be susceptible to rot or some sort of compression failure. An arch likewise may be bending or failing in some way.
One trick is to loosen off all the stays and measure distance between the floor or hull and the under side of deck. Then crank on the stay tension and check measurements. You may be able to find what is compressing. The atual cabin top provides some support for the mast but if the compression system fails then it will collapse downward.

I helped a friend receently who had this problem. The design had a compression post which went from under the mast at a slight angle forward and down. near the floor the post had a flange welded on the side so that the post was bolted to a strong under floor bulkhead. All Ok except the bols used were quite feeble 1/4 inchsuch that with down load sideways on the bolts they eventually after many years bent. The fix was to jack up the post and under deck and replace the small bolts with 10mm bolts and add 2 more.
I think however the best system is a post with packing under the bottom right onto the keel.
Anyway if you are considering buying the boat the problem could be a way of getting the price down and should not be a really difficult fix. You might even just add a post. good luck olewill

 

[sailorman]

I viewed a Fisher 25 that appeared to have a slightly concave deck surface at the foot of the mast.

I wasn't able to see the mast support system from inside the cabin - there is no compression post, so I assume there is some form of beam/support in the coachroof.

Does anyone know the mast support set up on these boats? - they are heavily constructed and I would have thought the loads imparted by the rig would be fairly small?

The mast loads on a Fisher 25 are not going to be very high, it after all a motor boat with a very small rig & not much accommodation either for the length / money.
there must be better choices of vessel in that price range.
I await incoming flak

 

[Bilgediver]

I viewed a Fisher 25 that appeared to have a slightly concave deck surface at the foot of the mast.

I wasn't able to see the mast support system from inside the cabin - there is no compression post, so I assume there is some form of beam/support in the coachroof.

Does anyone know the mast support set up on these boats? - they are heavily constructed and I would have thought the loads imparted by the rig would be fairly small?

WHich Fisher 25?????? Pilot house or Freeward?

 

[gavin400]

WHich Fisher 25?????? Pilot house or Freeward?

Pilot house version

 

[Caer Urfa]

I viewed a Fisher 25 that appeared to have a slightly concave deck surface at the foot of the mast.

I wasn't able to see the mast support system from inside the cabin - there is no compression post, so I assume there is some form of beam/support in the coachroof.

Does anyone know the mast support set up on these boats? - they are heavily constructed and I would have thought the loads imparted by the rig would be fairly small?

Hi Gavin

Most of the The Fisher 25's were professionaly built by Northshore yachts between 1971 and 1987 with some by Fairways Marine and about three hundred were built.

They were designed by Wyatt and Freeman and did not have a compression post 'under the mast' which you will find sits ontop of the main cross bulkhead beam just before the forecabin.

It is hard to comment without seeing it but I would just monitor the depression under the mast base, is there any 'star crazing ' in the area? also I suggest you just make sure your mast base is bolted down tight and there is no movement in the actual base plate.

You may also get some info from the Fisher Owners Group http://www.fisherowners.org/


Hope this may help

Mike