197? 240 Sea Hunter Build

[Tx49]

Oh chit, just saw it has the funky a$$ end, with that indentation that makes it damn near impossible to install a set of tabs...which you're most likely gonna need.

I was just outside looking at that myself. 2 things about that came to mind. 1. Can someone help me narrow down the year based on the hull details. It was a cC also. 2. If i am replacing the transom, can I not just cut all that out and put in a straight flat full height transom. Maybe build the new one with a little concave to it?

[seabob4]

Now you're thinking!

[Tx49]

I will start cleaning and prepping for the build today. I am trying to plan the hull work and have been studying the hull extensions i have seen, 2 here and one on iboats that another CAS member pointed me to. If you remember from my previous posts I want to extend the hull 3'-0". I have tried to use what I have seen on these threads and others to come up with my plan. I would like to spell it out and hear some reviews from you guys.

Because keeping the shape is critical whether you are doing an extension, a floor/stringer repair, or anything else, I think I should build a cradle and brace system to hold the hull in its current shape. I would do this by caulking (good temporary glue, easy to remove) 2x bracing linearly down the sides, in the chine areas, the bottom. Then I would build the cradle frames to the outside of the 2x ledgers I have glued on. I would make the ledgers run 5' wild aft. Here's a rough sketch of the transom view looking forward.
Once this is completed, securing the hull shape, I would rebuild the transom. Because i have the "funky" transom, I foresee removing it completely and then rebuilding the new one from scratch. I would match the existing profile at the keel, chines, and sides, but I want to put about 2-3 Inches of crown front to back in the top of it. After the transom is replaced, I would take the inner hull down to nothing. Liner, floor, stringers, everything gone. clean it completely and line the entire hull with one layer of glass. Then I would cut off the stern 16" to 3'-0" forward of the transom(depends on where the straightest lines are). I would then slide the transom section back 3'0" to to create the space for the extension. after forming the mold, I would perform the glass extension similar to what was detailed in the iboat thread. After the extension glass is complete then I would stringer it and perform the rest of the underfloor work. I am not going to replace the factory liner and i am going to remove the cap, so I also want to extend a few bulkhead pieces up the sides as side/gunwale supports at this time, similar to a frame on a framed boat.


I have tried to take what I know of carpentry and concrete formwork, boats, and the best of the different threads to come up with this plan. I also hope that you guys will point out any holes or overkill in my plan. Although I might not use all the input all the time, I do want to hear it so i can weigh it out against all the information I have and make the best decision. I have also noticed that on these build threads, even if the advice doesn't help the OP, there is usually someone reading the thread who gets some good info for their own use.

[Tx49]

http://forums.iboats.com/boat-restoration-building-hull-repair/hull-extension-progress-pics-234392.html

link to the iboats hull extension.

[dburr]

Just curious while I ponder the way I would do this.. Why do you want the extra 3 feet? Interior space or longer planing surface?

Reason for the question is it changes how I would do the extension and even though you like the Bravo III, a water jet may be a better solution..
standing by..

[Tx49]

Just want a bigger boat.   When you say waterjet are you referring to a jet drive? Like a Berkeley? Ther's a 455 olds with a berkeley for sale a couple of hours away from me right now. I just didn't think they were a good option for these type boats. if you are concerned about the "patch" of extending the hull, I understand why, but I am not. I have seen some outstanding lengthening projects and have talked to a few boatwrights who say similar alterations are not uncommon. its just all in how you do it.

[gran398]

This is going to be an exciting project. Your original posted design...is it 24 or 27 feet?

[Tx49]

This is going to be an exciting project. Your original posted design...is it 24 or 27 feet?

Thanks. Its pretty daunting too. But I look at it like a building any building I build. It ain't rocket science. Just be patient, careful, and farm out the stuff that will cost you as much to do yourself and it should hope fully all work out.  (Yeah right- I'm scared to death trying this, but i'm going to do it)  The drawing was was taken from the brochure and then I lengthened it amidships and drew the cabin and bulwarks in. Its close to scale. After seeing the depth of the stringers, I know I will have plenty of room for the cabin i want.

[gran398]

The good news is we have excellent Master Rebuilders, Eugene at Shipoke who gives freely of his time, and access to other professional builders for guidance and advice. So although daunting and a lot of work...this is going to be fun

A potential time saver regarding the extension; leaving the deck cap (gunnel cap) on while the extension work is done may cut down on the amount of exterior cradle needed.

When the time comes to remove the liner; there is a thread here on removing the liner (deck and floor) in one piece. The entire part was lifted out from above with come-alongs and rope. Pretty much the reverse of assembly. It was an ingenious idea, you just flip it over and re-core the deck from underneath. This may or may not be applicable to your needs, but wanted to mention it. It is possibly a big money saver.

Looking forward to your project!

[dburr]

There is no problem with stretching the hull.  With the number of guys here that dig skinny water rides, I am surprised that this hasn't been done more often or that someone hasn't put a tunnel on a flatback ..

The question is where to put the plug and that depends on where you want the room.  The term “plug” refers to the built on/in hull extension..  A longer cockpit and the plug goes aft,  if you want more room forward for a larger cuddy or a big inboard,  then the plug can go amidships.  It would be harder to do there because of the flare and you don't want to interrupt the sweep of the sheer, but if that is where it needs to go then there are ways to fair it in.

The important part, and it looks like you have a solid on it, is the bracing to keep the hull shape as designed.  WRT the picture you are going the route of over kill but there is nothing wrong with that.  Go easy on the number of glued pieces (would be called ribbands in new construction) fastened to the hull, a little glue goes a long way when there is no shear load and she will be sitting static on a cradle.  When it comes time to take it apart with every piece glued you will be using language unbefitting a gentleman   .  If you are going to fasten them together, then by all means go easy on the glue.  Unless you plan on moving the hull or are worried about an earthquake it isn’t going to move.

For just adding 3 feet really think through your power options first.  If you are going with outboards and are going to use a bracket, that will add almost 30 inches to overall length.  It sounds like you are leaning towards an I/O, if so going straight off the stern will work.  Just measure carefully, if there is a significant decrease in the beam, to make it look “right” that decrease will have to continue and you don’t want to lose space or create a flat spot so the plug would go forward of the point that the decrease starts.  You would be essentially building a custom engine box and that opens up a pile of cool options to include adding more tumblehome to the shape of the stern, and with your desire for some deck camber add that to the flare and sheer she will look more Down East and that would be COOL!!

If you extend the chine and wetted surface you are going to increase you L/B ratio and that will make for a slightly lower power requirement for similar speed (long narrow= good/ short fat= bad).  Lots of really cool stuff going on.

Trim is going to be effected as well based on the location of the plug and if you are going to add a house/cuddy keeping track of weight is going to be a big deal to keep from putting things too far out of whack, all that work to have her down by the head would not be cool.

As far as water jets, yes, the Berkley type is what I am referring to, Berkley is one among many and they will work well on our hull types with little modification..

Not sure if any of this helps but you are going to have a cool project for sure.. Seems your on your way to a mini Bertam 32 and that is cool too!!

[Tx49]

Thanks dburr. That's a lot of the info I have been thinking about, but I was wanting to hear from others to tighten up and/or redirect my thought processes. As for the cradle, that is one thought I have had, but i would really like to come up with another because I have it sitting on the trailer and i would like to keep it there as long as possible. One thing I thought about was possibly leaving the cap and liner in place as long as possible, cutting out the floor and replacing the transom, but leaving all that bulk of the outboard well.and the casting deck in for the time being. Then do some lighter bracing to hold it together while I cut and install the plug. As to the hull shape matching up, I want to find the place aft where the beam, chines etc., are the most consistent and cut it there so that it will be very little fairing necessary. If there is not a good spot like that, if the lines are continually varying amidships to stern,  then I might as well just chop off the ass end and continue the lines out and build an entirely new stern, don't you think?
My big concern about the hull shape has more to do with the cap than anything. I am going to build a new cap and I think I need to save the existing one as a pattern. But if I lose any shape at all, I don't know how I will get it back, without the old cap. Thats why I am thinking about leaving the cap on until I frame the floor including gunnel support/side braces running up the sides. What I was thinking was making them out of cypress and above the floor just soaking and coating them with epoxy, for a clean natural wood look. These would not be every bulkhead, they would just be about 3 each side in the cockpit, aft of the cabin. The cabin will provide the structural support for the sides and gunwales forward. I hope this is making sense.

[Tx49]

...For just adding 3 feet really think through your power options first. If you are going with outboards and are going to use a bracket, that will add almost 30 inches to overall length. It sounds like you are leaning towards an I/O, if so going straight off the stern will work. Just measure carefully, if there is a significant decrease in the beam, to make it look “right” that decrease will have to continue and you don’t want to lose space or create a flat spot so the plug would go forward of the point that the decrease starts. You would be essentially building a custom engine box and that opens up a pile of cool options to include adding more tumblehome to the shape of the stern, and with your desire for some deck camber add that to the flare and sheer she will look more Down East and that would be COOL!!

I understand what you are talking about here just enough to get confused. If I go Inboard, it will be Inboard/outboard, unless I decide on the jet drive you mentioned. I would love to go with a more central inboard, but I think that would cause 2 problems-Not enough room to get it under the deck and not too much weight forward. So that opens the question about some of the customization you mention. I would like to discuss that with you in more detail. What are the benefits or advantages to adding tumblehome. I can see where I could just flare the existing in with the new and through the existing stern piece and have more tumblehome and pull it and hold it all together with my gunwale supports and a different shape to the transom, but won't that take away usable cockpit space. How does all of this tie in with your comment about a custom engine box, or is that just a general statement because I obviously have to have one and ther's not one now?

[dburr]

One thing I thought about was possibly leaving the cap and liner in place as long as possible, cutting out the floor and replacing the transom, but leaving all that bulk of the outboard well and the casting deck in for the time being. Then do some lighter bracing to hold it together while I cut and install the plug. As to the hull shape matching up, I want to find the place aft where the beam, chines etc., are the most consistent and cut it there so that it will be very little fairing necessary. If there is not a good spot like that, if the lines are continually varying amidships to stern,  then I might as well just chop off the a$$ end and continue the lines out and build an entirely new stern, don't you think?

If there is a constant change of dimension along the length of the hull then to get it “right” you will be most easily be adding to the stern.  The only way to figure that out is to get out the tape measure and a straight edge and have at it.. If you have a beam dimension of like 9’11 for the space of a foot or so that would be a likely spot to try..  Don’t just look at the topsides, look at the bottom too, it would not do to make her profile look pretty, too only build in a yank that you don’t want.  The only other way I know of to try and make sure that it would be correct is to take the extra step and pull off a set of lines and creating a table of offsets.  That way you can draw out a set of waterplanes and do a profile view and then stretch it how it looks best.  This step however adds a considerable amount of “non productive” work/time but would allow you to really see what was going to happen if you can’t walk up to the boat and see it in your head.

 

My big concern about the hull shape has more to do with the cap than anything. I am going to build a new cap and I think I need to save the existing one as a pattern. But if I lose any shape at all, I don't know how I will get it back, without the old cap.

If you pull off a set of lines you can horse an empty hull back into shape by measuring out to the baseline so you could tie the hull in a knot, pull it back into shape and still be ok as long as you have support AND have not glued stuff to it when it is out of shape..

Thats why I am thinking about leaving the cap on until I frame the floor including gunnel support/side braces running up the sides. What I was thinking was making them out of cypress and above the floor just soaking and coating them with epoxy, for a clean natural wood look. These would not be every bulkhead, they would just be about 3 each side in the cockpit, aft of the cabin. The cabin will provide the structural support for the sides and gunwales forward. I hope this is making sense.

Cypress knees epoxy coated would still need UV protection of something like varnish for the natural look or the epoxy will turn a gross milky white.  The knees will look great but will be toe smashers like the rod holders on my Osprey..  Look at what Scotty had done on Miss D for knees, great support but no smashed toes.

If you are going to take the deck off to get at the stringers you will lose lateral support for the hull and it is easy to unknowingly build in a twist without good support.  I think others may chime in, if you are really going to open her up then you will need a little more than trailer bunks to keep the shape right, not a lot more, but at least stringers and chine area with support under the forefoot. Especially when it is time to cut in for the plug

I understand what you are talking about here just enough to get confused. If I go Inboard, it will be Inboard/outboard, unless I decide on the jet drive you mentioned. I would love to go with a more central inboard, but I think that would cause 2 problems-Not enough room to get it under the deck and not too much weight forward.

The engine of a straight inboard will not fit under the deck unless you use an old VW bug or Porsche 914 opposed piston rig..   Engine weight goes forward, fuel and battery weight can come aft. And yes it is worth worrying about..

What are the benefits or advantages to adding tumblehome. I can see where I could just flare the existing in with the new and through the existing stern piece and have more tumblehome and pull it and hold it all together with my gunwale supports and a different shape to the transom, but won't that take away usable cockpit space. How does all of this tie in with your comment about a custom engine box, or is that just a general statement because I obviously have to have one and ther's not one now?

Tumblehome has no real advantage other than looking pretty to some folks, others don’t like it and yes it will narrow up the stern.. If you want to pull existing panels in to get more shape you have to be really careful how you do it and which way you pull.  I am not a structures guy so I don’t know all the cool words.  Best way to illustrate it is to get a stiff piece of paperboard (cereal box) and eyeball the shape of the side of the boat and form the cardboard to the shape of the hull.  Then move it the way you want to and see if  a panel will even bend that way.  You may be surprised at the ways that laminated panels will and wont bend..

Just thinking you have a chance for a way custom engine box, cool shape, built in tiki bar, "dancing" pole,  that sort of thing.. What ever you want.
This project will make you a custom, one off Sea Hunter 24+.  Again, WAY COOL!!

   

[gran398]

Dave, that was excellent

Tx49....any friends that are good with 3D CAD?

[dirtwheelsfl]

LOTS of good stuff up there ^            And don't forget, Form Follows Function!