Getting rid of a bottom hook...

[croSSed]

If I keep my present boat I'm going to need to replace the floor and stringers over the winter. My boat was manufactured with a hook in the bottom. I won't go into why they did (I know why they did) but I would like to take a little of the hook out of it; maybe not all, but some. One of the things I thought about doing was after I get the floor and stringers out would be to take the inner rollers off my trailer so that the weight of the boat was resting on the rollers at the transom and those near the bow (and release tension on the bow eye from the winch to allow the front of the boat to rest on the front rollers). In effect, the center of the boat would be without support so as to cause a sagging effect at the center of the boat, thus (at least partially) straightening out the hook, or so my theory goes. With the boat in this position I would do all the work of putting in the new stringers and floor. Once the work was completed I would put the rollers back in.

Questions: Would this have any effect on straightening the hook? After the work was done I can see a possible problem. The new stringers/floor would be trying to hold the bottom straight, while the hull would continually be exerting pressure against the stringers/floor to re-hook. Could this cause the stringers/floor to delaminate from the hull? Is this just a bad idea all-around?

TG

 

[Chris1956]

Re: Getting rid of a bottom hook...

The manufacturer's will generally engineer hook into a hull to assist in getting the stern out of the water. Is the hook in your hull at the transom? My hull has a triangular-shape bulge where the transom joins the hull.

You can remove the hook many ways, but you need to remove it equally on the port and starboard sides of the hull. I think your idea of glassing in new stringers with the hull supported fore and aft is a good one. You should also weight down the stringers (w/cement blocks) to force the hull straight, while the glass hardens. I wouldn't think it would come "unglued", if you glass it properly.

 

[croSSed]

Re: Getting rid of a bottom hook...

Thanks, Chris. Actually in my boat, the hook runs the full length of the running surface of the bottom. This is to keep the bow down so that it isn't "squirrelly" in a turn. This makes the boat handle like sports car, but severely limits the top-end performance potential. The hook is such that no matter how much you trim the motor out, you cannot get the bow up to get better top speed. I can get a little better top speed by trimming, simply because the motor is applying lifting force to the WHOLE boat, so the whole thing rises, but the bow doesn't move much. There are better ways to keep the bow down to make it corner in a stable manner, i.e., adjustable trim tabs.

TG

 

[sport15]

Re: Getting rid of a bottom hook...

Search for the thread on Dole-fin vs. Tiger tail, there are lots of opinions. If you try and take out the hook you are blazing new territory in hull shape and may end up with something that you really don’t like and can not un-screw up. On the other hand once you get the hull wracked to the shape you want and the stringers fastened in everything will hold its shape.

This part you will not like:

The only SURE way to get the shape you want is to build a strongback with frames and ribbands that define the shape you want then lower the hull into it and fasten it to it so you can GUARANTE that the shape is what you want and will stay that way while being re built. Lots of time and more $$ for the strongback.

Throw a fin or tail on before haul out and tell us if it helps. It’s a pile cheaper than some other alternatives..

FYI: A Dole-fin is about $27 delivered from amozon.com and might slow down the top end a tad, trim tabs are way more expensive, produce drag and will slow you down.

Dave

(I am pro Dole-fin)

 

[Chinewalker]

Re: Getting rid of a bottom hook...

As an alternative the the "strongback", a friend fixed a hooked bottom once by screwing a couple of 4x4s to the outside bottom of the boat, on either side of the keel area, while all the inner structure was out. He spaced the screws every 6-8 inches or so the full length of the hook area. I think he had a tack strip on the inside to prevent the screw heads from pulling through.
This effectively straightened out the hooked area. The new internal structure held the shape just fine when he removed the 4x4s and filled the holes with a bit of thickened epoxy.

- Scott

 

[sport15]

Re: Getting rid of a bottom hook...

Scott

He do anything to keep the twist out and how'd she perform when he was done?

Dave

 

[croSSed]

Re: Getting rid of a bottom hook...

FYI: A Dole-fin is about $27 delivered from amozon.com and might slow down the top end a tad, trim tabs are way more expensive, produce drag and will slow you down.

Thanks for the suggestions. I personally DON'T like Dolefins or the like, because they slow you down a tad, they require you to drill holes in your outboard, and you can't adjust them once they are on. Adjustable trim tabs only slow you when you have them down, exerting force on the water, pushing the bow down. If you have them up they don't cause any more drag than if you didn't have them.

As an alternative the the "strongback", a friend fixed a hooked bottom once by screwing a couple of 4x4s to the outside bottom of the boat, on either side of the keel area, while all the inner structure was out. He spaced the screws every 6-8 inches or so the full length of the hook area. I think he had a tack strip on the inside to prevent the screw heads from pulling through.
This effectively straightened out the hooked area. The new internal structure held the shape just fine when he removed the 4x4s and filled the holes with a bit of thickened epoxy.

- Scott

This is a very interesting idea, Scott. Better make sure the boards being used are true, though. Thanks for the suggestions, guys! I really appreciate it!

TG

 

[Chinewalker]

Re: Getting rid of a bottom hook...

Hi Sport15,
I don't think he did anything to avoid a twist. The boat was good and straight when he was done, though. The boat only had about a 3/8-inch hook when running a straight-edge from the transom forward 6-feet. It was also readily visible by sighting down the keel from the transom. He just ran drywall screws right through the glass into the 4x4s. They were probably 4-6 inches either side of the centerline of the boat, about centered between the keel and the stringers. Sighting down the keel when he was done looked perfect and symmetrical. I've seen boats that have taken a twist and you can usually see it when you sight the keel - the areas either side of the keel aren't symmetrical...
The boat performed nicely when he was done. His was a derrelict that was sitting in a field on a beam a couple feet in from the transom and had taken a set where the weight of the boat rested on the keel. I don't know how this would work on a boat with a built-in hook...

- Scott

 

[Tail_Gunner]

Re: Getting rid of a bottom hook...

I had the same issue with a boat i am currrently redoing. You might want to see get some input from ondarvr
or Dhadley on this subject, from what i have read its more trouble than it's worth.

 

[sport15]

Re: Getting rid of a bottom hook...

Thanks for the word Scott, I've seen the hog pulled out of wooden boats the way you described but then on goes the ribbands and bracing... Nice to know it works on glass boats without all the extra framing.
Dave