197? 240 Sea Hunter Build

[Tx49]

Well it rained yesterday. i am going to try to get a lot of measuring and control lining done today. I think right now everything hinges on the lines of the boat and where the extension is going to occur. That will decide what gets torn out first, how I support it, etc. So I need measurements to decide that.

[Tx49]

Dave, that was excellent

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

A few actually. I need to get one over and see what we can come up with.

[Tx49]

Ok let me get this straight if I can-
dburr is Dave, Gran is Scotty Matt is dirt wheels.  OK. thanks for all The input. As well as SeaBob and others. You guys are really giving me confidence on this build.Now another question.
The stringers on this boat are TALL. There is an insane amount of what appears on the surface to be wasted space. I know that under the cabin I will be lowering the floor to make a step down.  Is there any reason I can't lower the rest of the floor also. Right now the self bailing, the best I can tell just runs bails into the bilge. Are the high stringers solely for purposes of self bailing? Seems like if I lowered the floor, that with the extra weight I am adding, it would help on both the center of balance or flotation (I think that is the correct term) and would also effectively make an increase in freeboard. Or should I actually want to be raising the floor in the back. I am mainly concerned with sea worthiness and bilge pumping/self bailing in regards to that, not the maintenance side of getting the water out.

[love2fish]

[/quote]I am mainly concerned with sea worthiness and bilge pumping/self bailing in regards to that, not the maintenance side of getting the water out.[/quote]

The 2 are hand in hand... a dry boat is gong to be much more sea-worthy, whether thats when the boat is sitting at the dock in a down pour or your are underway and have waves coming over the bow, or have a bunch of people sitting in the boat at the sand bar. remember even on the water- gravity is your friend and water will look for the easiest way to flow- so I would not lower your stringers if possible. the benefit you will gain in weight will be marginal at best and the benefits to having the floor as high as possible far outweigh that... I would suggest having some kind of scupper so the water on the deck flows directly out through the transom or gunwale (as some have done)...
you will see when you start re-foaming- the foam is extremely light when dry- so I would concentrate on keeping your foam dry by building/rebuilding strong/solid stringers and making sure to seal them up when you re-do your floor.

given that you'd like to add the big cabin on a fairly narrow boat-I think the seahunters are under 9' wide,,, your COG is going to be pretty crazy even if you drop the floor a couple inches- might as well have the higher floor to compensate for that extra weight.

[orb]

Tx49,
I added a 3' extension to the hull of my 240 seahunter. I am still rebuilding it, bit I am pretty much done with the extension, just finishing up with the stringers now. If you want to talk and get some ideas, you can give me a call. Private message me for my number.


As for the stringer height, I would not monkey with the stringers, except to get the old foam out, refoam, and possibly retab them back to the hull up in front of the console. As far as the height goes, I agree with the others, having a higher freeboard will help the boat self bail better. To me, it is kinda like a tug boat that can take huge amounts of water over the sides onto the deck, but the deck is so high, it runs off very quickly, through the ample sized scuppers/drainage holes.

The 240, especially stretched, has many of the characteristics of the dorado 30. Beam to length ratio, bigger bow,  lower deadrise, higher freeboard. This does allow for alot of storage under the deck.  Check out the dorado 30, that is where I am getting alot ideas for my rebuild.

[Tx49]

Tx49,
I added a 3' extension to the hull of my 240 seahunter. I am still rebuilding it, bit I am pretty much done with the extension, just finishing up with the stringers now. If you want to talk and get some ideas, you can give me a call. Private message me for my number.


As for the stringer height, I would not monkey with the stringers, except to get the old foam out, refoam, and possibly retab them back to the hull up in front of the console. As far as the height goes, I agree with the others, having a higher freeboard will help the boat self bail better. To me, it is kinda like a tug boat that can take huge amounts of water over the sides onto the deck, but the deck is so high, it runs off very quickly, through the ample sized scuppers/drainage holes.

The 240, especially stretched, has many of the characteristics of the dorado 30. Beam to length ratio, bigger bow,  lower deadrise, higher freeboard. This does allow for alot of storage under the deck.  Check out the dorado 30, that is where I am getting alot ideas for my rebuild.

Orb,
Yours is what got me originally thinking of a aquasport 240. I was going to build a wooden boat 26-27 feet. I saw this boat on craigslist and decided to research it. i saw your extension project and decided to buy it and build my boat based on this hull. I will be removing the entire stringer system. While there are good aspects to the AS Stringer system, there are many downfalls also. I will be going back with a stringer and bulkhead system. i have many reasons for getting rid of the trapezoids. Too many to go into here, suffice to say its not arbitrary and has been well researched and thought out.
Freeboard-Maybe I am misunderstanding the term. I thought that freeboard referred to the height from the waterline to the cap. If so I don't understand how raising the floor will increase freeboard.

Orb and love2fish--I have actually considered raising the floor in the cockpit as much as 3"-6". I think it would be really cool to have a couple of bronze scuppers a couple of inches above the waterline self bailing. With a bulkhead across the cabin entry, I think it would stay pretty dry that way. The beam on a seahunter is 8-0. As orb said, the L:B:Draft ratios of an extended seahunter is very similar to the dorado 30. That being said, I think love2fish may have misunderstood what I was saying about the weight and center of balance. Because i am adding some high weight with the cabin, If i lowered the floor it would bring that weight's moment down lower in the hull, stabilizing it more. I wasn't trying to lessen the weight by lowering the floor, I was trying to literally lower the weight. I have to lower the floor to make the cabin work, and that is a common condition with any kind of cabin, but maybe your right in regards to the cockpit floor and i should go ahead with raising it. I assume the weight of the inboard being at the rear and low will also help counter some of that extra cabin weight. Keep in mind that these came with an option for a flying bridge tower that was at least a foot taller than the cabin flying bridge I have planned.

[gran398]

You definitely want to keep the stringer height in the cockpit area the same. You could raise it some, but 5 inches IMO would be unnecessary. You are killing the freeboard (the height from the deck to the top of the gunnel) by raising the deck that much. Don't want your crew falling out if you can help it.

A way to increase the freeboard yet still raise the deck would be to increase the height of the gunnel cap. Take a look at the CCP's....they have plenty of freeboard due to taller deck caps (gunnel caps)

The cabin is another story, you could lower the stringers there so you "step down" into the cabin as you would in most cabin boats. Just remember to install a good bilge pump in the forward bilge.

[Tx49]

You definitely want to keep the stringer height in the cockpit area the same. You could raise it some, but 5 inches IMO would be unnecessary. You are killing the freeboard (the height from the deck to the top of the gunnel) by raising the deck that much. Don't want your crew falling out if you can help it.I may have forgotten to mention that I will be adding a 4"-6" bulwark

A way to increase the freeboard yet still raise the deck would be to increase the height of the gunnel cap. Take a look at the CCP's....they have plenty of freeboard due to taller deck caps (gunnel caps)

The cabin is another story, you could lower the stringers there so you "step down" into the cabin as you would in most cabin boats. Just remember to install a good bilge pump in the forward bilge.

Yes had definitely planned to have good bilge pumps. also will have good bilge drainage to the rearWill be installing plenty of limbers and at least a couple of limber chains.

[dirtwheelsfl]

Id probably raise the deck a few inches to ensure a self bail with the weight being added. As far as keeping the weight down in the hull, you can play around with different materials to get lighter up top. If you decide you want more freeboard after the deck is in you can add some rails to the inside of the cap. Youre going to be doing a lot of cap mods anyway with the cabin and whatnot..    Chris by the way...

[dburr]

We’re starting to hack up a few terms I think..

Not being a dink, this is right out of my old ABS/MARAD stability book.  

Freeboard: height of the deck above actual waterline ie surface of the water.

Topsides: height of rail (gunwale-gun'nl-gunnel) above the water.

Center of Mass (Cm): the actual center of mass of the vessel.

Center of Buoyancy: (Cb) actual center where all buoyant forces act on the vessel.

That way when I start going all yankee on you southern boys none of us will get confused..
   

Lowering the deck a few inches will not get you a less tender (softer/slower) rolling moment, keeping the house light, adding an I/O (think all that steel)  and of course batteries/ fuel/water tanks as low as possible will.  The deck as a unit of mass,  if you use light materials, really will not be a significant factor effecting the rolling moment distance between Cm-Cb.  The boys that have done cored decks will tell you that 2 big deep cycle marine batteries will weigh more than the deck will.  Put those on a battery flat in the bilge and issue is moot.   3 250 guys on the Fly Bridge will….  


All good!!  Lets see some numbers!

[Tx49]

OK. I am starting to see that while my thought process of the lower cockpit floor theory  was right, the actual real world application was going to be negligible. So raising the floor it is. But this suddenly brings another item into play. Right now the stringers at front of the old CC are 20". If I were to raise the stringers 4"  (Remember I will have the added 6" bulwark.)I could fit a central inboard under the deck, maybe a small step needed. Then I could run a direct drive. is this a better drive system or should i stick with a stern drive be it I/O or jet. Would this make it excessively hard to plane with 900-1100 pounds 8-10 feet from the stern? I know I'm probably being a PIA, but I just need to review so many options before I start cutting.

To recap though-right now I am still looking at a cockpit floor that will be raised 4"amidships, 3"at the stern, and 3" at each side. This will give me a crown center to side and cabin to stern. I will be using a 350,351,454,455, or 460 with a jet or I/O drive. I will not be using a plug, I will be cutting off the transom and extending from the stern.

And yes whoever it was that said I was looking similar to a Bertram 31 (Dave, I think), That's the exact look I was going for.

And thank you to all. I appreciate everything I'm learning from you guys and your patience.


Johnny

[slvrlng]

I would love to see what this would do with your plan as now. Hey, its only 593 lbs with no running gear! Although, then again the jet would be cool. Are you going to run the bays over there or more outside?

http://www.yanmarmarine.com/theme/yanma ... asheet.pdf

[Tx49]

But I'm not sure if I can't count high enough to get to the price.   It will be a trailered lake, coastal boat, but I wanted the ability to go offshore aways too.

[dburr]

No problem Johnny!

There was a guy from Connecticut(?)  on here that posted about an inboard 222 center console. (just did a search of the member gallery look up OldSchool)  Putting a motor amidships with a straight drive is a perfectly fine option..  A point of trivia, putting in a gas inboard (straight or I/O) will affect insurance a bit.  I guess they underwriters get nervous that the internal combustion part is going be on inside of the hull  :bom: and not hanging from the stern and bang you for it.. Some folks have no sense of adventure . Makes no damn sense but that is business I guess..  If you opted for diesel they start giving you back bonus points, I guess because it won’t backfire and burn your face off.. (flew a guy to a burn unit two days ago that had that happen to him, it was gross)

The engine box, if you don't raise the deck to much, is a fine place for the Admiral and the dog to catch some sun.  Options and selling points!
 

For a straight drive options check out http://www.evolutionmarine.com/.  These guys are in Rockland Maine and have the most advanced, yet low tech/ low friction shaft system around.  Why them? They have about 0 friction power loss because they use mechanical seals not a friction seal like a standard stuffing box. Quiet, because of real honest soft engine mounts and they have less turbulent water flow to the wheel and that gets you better efficiency.  NO I do not sell them, nor am I tight with the folks that own the place.. I have worked on boats with their shaft systems and ones without.  Hands down Evolution was smoother and quieter and nowhere near as hard on your back and feet at the end of the day..  

6 inches to the rail height is going to be alot.. Whazza plan for flairing that in so it doesn't look chunky?

There is a picture in the gallery of a West Coast style house top on an Explorer and boy did it turn out pretty (serious workboat look), I wish I could remember who did it.  It wouldn’t look like a Bertram, but it would look good!  Hopefully one of the more senior Brethren will remember, he was/is a west coast member.

[Tx49]

Well finally got to do a few things.

First, I lowered and leveled the trailer left to right.. We took the tires off and set it down on 4x4’s directly on the axles. Sorry no pics of that.
Then after leveling it at the transom, My  youngest son and I eye-balled the center of the transom VEE and plumbed up from there attaching a 2x marking the C/L. It looks caterwauled in the photo, but that is an optical illusion

Then we eyeballed a centerline on the front. This was a little difficult to get right as the hull vee, the rubrail point, and the cap point were all about ¼” different from each other. That’s why went with eyeballin instead of measurements.

After we set those 2 centerlines, we added cross member supports to the cap at specifically measured points making sure they were perpendicular to the center string line.

After doing this, I got some good news. We measured a series of diagonals, aft to stern control points, and beam measurements from the centerline outwards,  up and down the boat. None of our measurements were more than 1/8” different. This boat is square, plumb, and centered. That is due to the factory, not me is what I am trying to point out.
After we got the centerlines completed, we jacked up the boats bow to let yesterday’s rain out. Probably a hundred gallons or more in there. It was well over 6 inches deep in the bilge all the way to the bow. (That was obviously not just yesterday’s rain). This photo is after over an hour’s draining.

You can see the water draining from the transom here.
After finding this water I decided to make a ridgeback to support a tarp. Just used some 1x1/4 nominal cutoff pieces that I have kept around here in case I ever needed them. Well they came in handy for this.

 
Here is the first cut. Across the deck to casting deck intersection. Started sawzalling and a kajillion ants came running from below. Probably can’t see them in the pic. They were tiny little boogers. Haven’t seen those kind around here. Hope I haven’t brought an invasive species in. That’s what stopped my work for the day-I sprayed the crap out of them and that area with pesticide.Then it started raining and now I have fresh pesticide everywhere. Figure I will give it 24 hours to dissipate some.


More coming.