How to remove "hook" from bottom of boat.

Par thats good post but , he has one very weak boat, and that boat needs some stiffening no matter what
I know nothing abiut sticky stuff like fibreglass, so will leave you and Charm and a few experts to it

[jimslade]

Set the boat on three outer points. Front on the V. Back two outer strakes. Use straight 3x3 box channel steel inside an out apprx. 6 ft long,bolt together outside the inner stringers. Leave for a week. Glass new inner stringers in. Don't touch the bottom with the wood. 3 layers of glass will work. Let cure 21 days relocate steel supports to outside of outer stringers.do same for outer's. glass in holes from support bar bolts. finish and forget it. I'm not a fan of wood, your just asking for more work later.

[PAR]

You're right Lazeyjack, the laminate is pretty weak, but he knows what he has and beating him in the head about a Bayliner's scantlings, will not get anything accomplished. I too, am concerned about the conversion to a transom hung outboard (and structural requirements), but he's asking about the hook. Your practical 'glass experience makes you a very valued contributor to this and other threads.

hey I,m not at all being facetious. i really do not know much abt glass, truly

[H180DSC]

I'm afraid I may not have been totally clear. I do understand that this is a weak hull, and the pics I posted are with the 4 original stringers and 1/2 of the original transom removed. My plans involve a lot of hull reinforcement including thicker transom and stringers with transom knee braces (all fully encapsulated in epoxy and glass) I also plan to add at least one more layer of glass to entire inside of hull for strength (possibly 1708). I started with the question about the hook in hull, because it seems to me that I need to have the hull straight before adding anything to it. Again, this build is mostly for the learning experience, and I want to do it right. Start with poor design and improve upon it. Is this not a good way to learn all aspects of proper boat building??

um no it is the wrong way , in my opinion,
Just a suggestion, but, would you consider builder yourself a new boat , out of ply or double diag, ?
ByTHE WAY I DONT SELL PLANS) I admire your tenacity, good luck mate

[charmc]

Dan,

No, I think you've been pretty clear. In your first post you said you are planning to add 1.5" plywood, glassed in to reinforce the transom, plus knees from the new stringers to the transom. Lazeyjack has focused on being sure to make the stringers extra strong, "girders" in his words, and the rest of us are just trying to get that message across of being sure to do what it takes to make the hull and transom stronger. Par has said it is best to give the hull a longer time to take the new set once you've braced it and used jacks or weights to bend it true. Sounds like good advice, also; the point, it seems, is don't force the hull into a new set with the stringers, that will just cause problems down the road. The purpose of stringers is to prevent future distortion of the hull, not to correct a current problem. So correcting the hull sag and installing new stringers are 2 separate procedures. No one is trying to beat up on you, it's just that fixing problems caused by others is sometimes harder (as you'll find out) than building a new boat, and these guys genuinely want you to succeed.

You understand it needs more than a simple fix, you're asking for advice to be sure you understand all the procedures and issues involved, and you're prepared to do the work. When you're finished, you're likely to be a pretty fair expert on boat repair, ready to help others who will be the beginners!

[H180DSC]

Thanks to all who have contributed to this post. I have found through all of this that it is easy to misinterperet words of wisdom from intelligent builders. Sometimes I start to get a little discouraged. I just need to take this project in small steps. You guys are trying to keep me safe, and not overlook major structural components of the build. I plan to post pictures of this build as it progresses, and hopefully you guys will continue with your guidance and not get too tired of my endless questions.

Dan

the thing is mate, when you have finished this boat, it will still be a dog, the entry is so flat and spoonshaped that it will slam badly, it is a smooth water boat You will need build a well or have the outboard on a pod, you must do what you want to do, we will all support you

[H180DSC]

I have nothing but time on this project. I will be taking the boat off of the trailer this weekend and putting it in the garage. I will build a cradle as was previously suggested, then build bracing from from the roof trusses to slowly push the hull into shape. Not sure how long to let it set once it is pressed into shape. If I plan to add another layer of glass to the inside of the hull should this be done before or after stringer installation? Is another layer of glass necessary, and if so is one layer of 1708 sufficient? Any other suggestions for making this hull stronger besides what has been discussed?
Thanks

Dan

[jimslade]

I just looked at the pics. You should not have removed all the stringers and transom. without proper support. I would scrap the boat now. The hull can settle and twist without proper support and bunk trailers have limited use. Also glassing to support an outboard is complicated on this type of boat.

[PAR]

Dan, I think you should continue with your ideas of improving the hull structure. Though this boat isn't the best choice, it's the one you've got so see what you can do.

I don't think the hook is particularly bad, I've seen much worse, which still were in operation. The hook will develop some drag, but not enough to get excited about.

Find out how much hook you actually have. You can do this with a long straight edge and place it against the lifting strakes, bottom centerline and flat areas between the strakes. The last portion of your hull should be damn close to dead nuts flat, in the fore and aft dimension. This area is called the run and is where the boat literally sits when up on plane. Any reverse curves in this area will tend to pull the bow down (not a bad thing on some designs, even built into a few), but your boat doesn't have any "designed" hook that I know of. Place the straight edge on the transom and see how much air space is visible, which will likely be just forward of the transom. It doesn't take much hook to effect the performance of the boat, but less then a half an inch and you really shouldn't worry about it, just reinforce the hull, hang an engine and have fun. After you checked the hull, it's a lot easier to work on them, if you don't have it on a trailer and they can be better supported for wandering around the inside as you fix stuff.

The first thing I would do it get it off the trailer and on a cradle, preferably one that has wheels, if your shop is anything like mine. You can stuff it back into a corner when you're not working on it and drag it out when you've got some time to put in her. These are usually simple 2x4 affairs, cross braces, triangulated stands along the chines, keel blocking, wheels, etc. Enough to support the boat, provide a solid platform for repairs and not distort the hull further. You can hack it up, when your done and use it to build a garden bench, for the other half when you're finished or chuck it in the scrap wood pile, for your next project.

If you've decided to remove the hook, you have to plan how you'll do this. There's really only two methods, force it back into place or make relief cuts and patch the repositioned areas with more glass. The forcing method is really a judgment call, usually based on experience with how much deformation you think you can twist back into place, with minimal laminate damage (highly problematic). The cutting method means you'll literally have to reshape the affected areas under the butt of your boat, restoring the laminate in the process.

If you elect not to fix the hook, or decide to just fill the area with putty and go with it, then you're only left with fixing the stringers and transom reinforcement. The hull is weak for several reasons, but much has to do with the manufacturing method and quantity of material used. In order to get any performance out of such a burdened hull shape, these boats were built as light as practical. It saved the manufacture building costs and the light structure could be propelled with a smaller drive. In this vain, I wouldn't add additional cloth to the hull proper, but just reinforce known areas of weakness, like the stringers, transom and it's supports (conversion to outboard power). The reason is simple, the biggest performance killer in small craft is weight.

Structural considerations for the outboard conversion would include a full width bulkhead to support a splash well, some knees and tying it all together with the bottom structure (stringers, etc.). This is a bit much to describe in this format, but if you'd like to contact me, through email (click on my name), I could provide you a reasonable laminate schedule and structure upgrades, that would prevent the transom ripping off the first time you hammer the throttle, while still keeping the boat light enough to supply good performance, with the engine you intend to use.

[marshmat]

Well, Dan, it looks like you have your work cut out for you.
Pay close attention to PAR. The guy's dead right, as usual.
I'd get her off that trailer and into a well braced cradle ASAP. The hull skin alone can just barely support its own weight, it needs external support while you rebuild the stringers.
As far as the hook goes, I'd be inclined to go with the earlier idea of putting sandbags inside the hull once she's on the cradle. It probably won't eliminate the hook completely but should reduce it to a manageable level.
An outboard applies a massive force to the end of what is essentially a big lever hanging off the top of the transom. It will tend to punch the centre of the transom forward and pull the top of the transom aft. Two or three large, well-glassed knees will be needed to brace the new transom. Adding a bulkhead slightly forward of the current transom, so you can add a splash well, is a very good idea.
You're in for a challenge, Dan, but I think you'll find the experience worthwhile in the end.

[jim lee]

Removing "Hook" is -very- common with the Hot Rod Jetboat crowd. From what I've seen them do and what I read here on your post I'd go at it in this order..

Set the boat somewhere. A cradle like mentioned above sounds good. Put in the stringers and transom. Don't try to force any hook out at this point in time just glass them in like it sits.

Now, the jetboat boys flip their hulls onto a bunch of truck tires so its upside down.

rough up the gelcoat with 36 grit. You don't need to sand thrugh the color.

Measure from the transom forward 6' with a straight edge. Do a topo map of the amount of hook using a sharpie. I think it was evey 1/8" depth. (Not sure about the depth but 1/8" sounds right)

Cut glass cloth to match these shapes.

Glass them into the low spots.

Once this fires off puddy over them with your favorite marine filler.

Sand it smooth.

Coat it with your favorite undercoat. The Jetboat boys use some sort of slick teflon kinda' stuff.

flip back over and your finished.

I've seen a pro do this from start, flipping hull, to finish, back on trailer in one day. Granted, this guy had done a LOT of hulls so he knew every trick in the book. But pretty much, this is how he did it.

Hope this helps.

P.S. There is nothing wrong with doing a project just to gain knowledge. Heck that's what school's all about. Go for it!

-jim lee