Reinforcing a tender bottom?

wragges

wragges

Well-Known Member
Joined
7 Nov 2005
Messages
145
Location
Nottingham, UK
www.minstercomputers.com
Hi All,

I recently purchased a second hand tender 8'x4' as a means of getting to our swinging mooring.

The boat is generally in good condition, except that the hull material is rather thin...thin enough to make it creak and grown (like gelcoat cracking) when you stand in it on the water.

At sometime, somebody has applied a couple sheets of Glass Fibre (CSM) on the outside of the hull (I assume to reinforce it) but that was insufficiently glassed-in, So it is coming away from the hull.

I therefore have to re-reinforce it again. I was thinking of doing it from the inside this time, using Epoxy resin pasted on nice and think in the bilge areas and up to around mid-topsides.

Should I put CSM in too, or do the panel think that would be an over kill. Weight is not an issue as we will use wheels to launch her.

Thanks,
 
CSM will not work well with epoxy, so dont bother with the expanse, use polyester.
What I think you need is something like tophat longitudinals to stiffen up the large floppy panel.
 
Yes. I have a grp dinghy as a tender and the skin is very thin. My floor also flexes and creaks. Especially if Mrs Lakesailor mounts the tender before launching (not make suggestions about her mass, just keeping her feet dry.)
I too thought that floor boards will be the ideal answer. Not too thick, just some 6mm ply, possibly with extra sections of the same bonded on from chine to keel to help dissipate the loads to the more rigid parts of the boat.

tender2.jpg
 
Being new to all of this (albeit totally obsessed since August!!) I am at least still able to recognise that while no one else on here seems to have batted an eylid about it, it is just possible, that just one or maybe two (hundred) non-boaty people might giggle at the subject heading....! How long do you think I've got left until I'll be concerned about reinforcing my tender bottom without the aid of dhiahoro /forums/images/graemlins/grin.gifcalm?
 
Probably the floor boards idea might be the best solution. However if you want to stiffen the skin added layers of glass and resin will help only slightly. You need what is known as triangulation in the structure which basically means thickness (better described as height) of skin for stiffness.
So a few cross members of f/glass that are maybe 1/2 inch high and 1 inch wide will provide great stiffness. This can be acheived by fitting wood or even foam battens then fibreglassing over them.
The battens in profile must be rounded on top so glass will sit close to the batten with no air bubbles and similarly you need to put in a bead of filler in the corner where the batten meets the bottom skin to allow glass to lay close to the batten. It won't follow a tight corner. Use epoxy and several layres oif glas to give 2 mm at least glass thickness. (and of course smooth out the batten at the ends as well. good luck olewill
 
agreed, and his extra-glassing-in may add too much weight.

I would want to be sure that something worked before making it permanent.

How about geting some toughish expanded polystyrene say 1 inch thick if poss, and plonking down a sheet of 3/8 ply on it. No need to glue it initially, just give it a try. This gives exactly the effect williamh is describing - and the thicker the polystyrene the more "spread-around" the load and the les should be the creaking of actual hull.
 
Why? 1 - did the previous owner glass it outside? maybe he was dragging it over a rough launch area....
2 - do you want to re-inforce ? Is the punt unsafe or wearing thin? Do you have a trolley/ launch rough? Perhaps some external sacrificial wooden stringers bedded on sikka screwed through the bottom would do, and they needn't add much weight. Plus it'll row straighter....... 73s
 
You must log in or register to reply here.

Share this page

Top