Author Topic: BobC's build in Virginia  (Read 5101 times)

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BobC

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BobC's build in Virginia
« on: January 02, 2016, 09:07:30 PM »
Well, I feel like I finally have accomplished enough to start posting up my progress.

For those who missed the intro or some of my ramblings on FishyFish, I am building a GA kinda like myself.  Short and stout. ;D  Due to build space restrictions, I have shortened mine to 24'6".

I have also extended the chine flats to 5" and put a slight reverse angle on them of about 4 degrees.

Both these minor mods seemed innocent and simple in the planning stage but they have proven to be quite a challenge when combined together in the same build.

Being that this boat is on the short end of the spectrum for a GA, I have used 1/2" A/B marine fir for the aft portion of the bottom panels and used 1/4" 1088 Meranti for the forward portion rather than 3/4" and 3/8 respectively.   

I'm on a tight budget for this build so I have also moved things around a little to maximize the use of each plywood sheet.  In the pictures, you will notice there are only 3 sheets of ply used for the bottom panels rather than the typical 4 peices with forward and aft cutoffs.   This reduced waste and the number of scarfs needed.  Downside is it required moving all the scarf joint locations and layout as given in the plans.  This couple with the thinner plywood fewer scarfs and shorter length of the scarfs due to thickness change has made things very interesting.  What I have saved in money, I easily have lost in time and complexity, but as a bonus I am saving a little weight.

The bottom panel molds had to be adjusted a little to work with my shortened length but everything seems to be laying and measuring up pretty nice.  The wider and angled chines are challenging me a little but nothing I can't work out now that I have it set up in the molds.

So I now have the bottom panels cut, scarfed, and placed in the molds and I am ready to begin taping the seams.

I'm learning a lot in this process.

 


Brian.Dixon

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Re: BobC's build in Virginia
« Reply #1 on: January 03, 2016, 10:21:34 AM »
You only moved the aft molds, not the bow region molds, right?  For 24'6", should be pretty close to the spacing used for the 25' version spelled out in the manual, minus 6" cut off the stern.  For the negative chines, I think you're doing great with 4 degrees negative on those.  Should be able to just just the downward angle on the chine flat portion of the molds and don't worry about the additional width ...the stock width will support the chine flats just fine.  And yes, 1/2" bottom for the 24'6" should be fine as well.  Glad you're getting started ....everything looks great!

Brian


BobC

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Re: BobC's build in Virginia
« Reply #2 on: January 03, 2016, 09:00:25 PM »
Brian,

Thanks for the feedback.

Brian,

I started out with the stock 25' mold spacing.  Due to space in the garage, I decided to shift everything back on the jig platform a bit so as to more or less center the boat and molds on the jig rather than starting 16" from the bow end as in the plans and have space left over at the stern end.  Unless I missed something critical, it looked like this would be fine for all steps until the bottom is flipped over and the stem beam and stem attached.  I will likely have to make some changes then to keep it all under roof as well.  I have 8" of the stern hanging off the jig and about 16" overhanging at the bow.

That said, I kept all the distances between molds stock.  Once this was done I made some adjustments to the two aft molds account for the 6"  difference between my bottom and the 25' bottom.  Then I took a look at where the edges of the bottom panels fell on the molds in relation to the chine flat transition point.   Everything fit pretty good and lined up OK but the transition from Mold 2 to mold 3 seemed a bit pinched with the forward two molds creating a bit of a hard spot in the fairness of the curve at mold # 2.

 I suspect this is a result of me using the 1/2" and 1/4" inch  which bends at a little different rate being not as stiff as 3/4" and 3/8"?  Anyways, to eliminate this hump at mold 2 I adjusted the forward molds slightly forward  :(

My spacing ended up as follows:

From the bow tip, the aft face of Mold 4 is at 72" Mold #3 is at 134" (62" spacing) Mold #2 is at 190" (56" spacing) and Mold #1 is at 242" (52" spacing) and the bottom extends exactly 12" beyond the aft face of Mold #4.  The overall length of the bottom panels is 21' 0".   

I could perhaps have moved mold # 2 back slightly to ease the transition but that seemed counter intuitive with a shorter hull.

All critical measurements seem to be right as far as I can tell.  The 37"X  41-5/16" measurement is dead on no real spreading force was required at the 2x2 spreader.  No stitches seem to be stressed.   I was surprised at how well it all fit.  Nothing is committed to epoxy yet so I can still play with them if you think I should taking pictures to show results or other measurements and tweeking it a bit?
 
The transom panel matches up nicely with the bottom panels.

The chine angle has made lofting the chines a bit tricky but I think I have that worked out as well.  Epoxy should be set on my template scarfs tomorrow and I plan to check both sides with it for symmetry before I go any further.

I am doing as-built drawings with dimensions as I go that cover my modifications.  Would be happy to send them to you if you would like.

Brian.Dixon

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Re: BobC's build in Virginia
« Reply #3 on: January 04, 2016, 07:21:55 AM »
If you eye-ball the panels from every angle that you can and all the curves appear fair and smooth, then you're good.  The adjustment from 25' down to 24'6" isn't that  much.  With the stern out over the end of the jig, make sure you support the transom appropriately when you install it ...look carefully at the shelves to make sure they aren't bending down oddly at the stern due to the (OMG heavy) transom weight.  Otherwise, all sounds fine.  I didn't take the time to go figure out the measurements, but everything looks good from what I can see in the pix.  The boat will be great ...  ;D

Brian

BobC

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Re: BobC's build in Virginia
« Reply #4 on: January 04, 2016, 08:14:18 AM »
Thanks for the great feedback.  I will continue to press forward and keep posting pictures of the progress.  Hopefully some more work tonight on the chines.

Dave Collett-Paule

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Re: BobC's build in Virginia
« Reply #5 on: January 04, 2016, 10:20:26 PM »
Looking good, Bob!  Keep at it!

Dave in Homer

BobC

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Re: BobC's build in Virginia
« Reply #6 on: January 05, 2016, 07:14:48 AM »
Thanks Dave.  I have been going back through some of the older threads and doing some researching on chines and ran across your build with the splash rail/mini-reverse chine that you did.  Your boat looks incredible, you did a great job and have inspired me.  Also good to know that I am on fairly solid ground in pushing forward with my slight reverse chine effort based on your performance reports. 

Brian.Dixon

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Re: BobC's build in Virginia
« Reply #7 on: January 05, 2016, 09:02:01 AM »
Thanks Dave.  I have been going back through some of the older threads and doing some researching on chines and ran across your build with the splash rail/mini-reverse chine that you did.  Your boat looks incredible, you did a great job and have inspired me.  Also good to know that I am on fairly solid ground in pushing forward with my slight reverse chine effort based on your performance reports.

...If I were to re-do the design a tad right now, I'd probably increase the waterline beam by 2", add around 4 degrees negative angle to the chine flats, and perhaps make the half-angle of entry a degree and a half finer (noting that these are very small tune-ups - I tend towards being a perfectionist).  You're doing the right thing... :)

Brian


Cannon

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Re: BobC's build in Virginia
« Reply #8 on: January 06, 2016, 07:48:22 PM »
Bob,
You are doing a bang up job! Take your time at this stage and make sure everything lines up and is fair. What happens now will determine how easy the rest of the build goes, especially when you set it down on the stringers and stem. Line it up, make sure everything is just so. Once you have things just right, the rest is a snap!
Remember, the ark was built by amateurs; the Titanic was built by professionals.
Started building Paula J the 2nd Week of June 2015, finished her the second week of July 2016.

starbright55

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Re: BobC's build in Virginia
« Reply #9 on: January 11, 2016, 09:48:07 AM »


Thanks Dave.  I have been going back through some of the older threads and doing some researching on chines and ran across your build with the splash rail/mini-reverse chine that you did.  Your boat looks incredible, you did a great job and have inspired me.  Also good to know that I am on fairly solid ground in pushing forward with my slight reverse chine effort based on your performance reports.

...If I were to re-do the design a tad right now, I'd probably increase the waterline beam by 2", add around 4 degrees negative angle to the chine flats, and perhaps make the half-angle of entry a degree and a half finer (noting that these are very small tune-ups - I tend towards being a perfectionist).

Brian,  and how would you accomplish this? 2" to the chine flats, wider bottom panels, or a combination of both?



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Brian.Dixon

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Re: BobC's build in Virginia
« Reply #10 on: January 11, 2016, 11:38:33 AM »
I would re-loft the bottom panels to make them wider. 

The reason that I would go 2" wider is because the original design is conservative in terms of where the DWL is.  The boat sits in the water a little deeper than necessary - this hedges your bets against high speed instabilities such as porpoising.  There are enough GAs on the water, working in a wide enough variety of conditions and loadings to show that the design can be a little less conservative.  If the DWL were a little lower (the boat floating a tad higher), then it would give the boat additional capacity and additional gas mileage.

If I re-loft the bottom panels to make the bottom panel assembly 2" wider, then this displaces more water (making the boat float higher) than if you just made the chine flats an inch wider on each side (which hardly displaces much additional water and has next to no impact on the waterline).  Sketch it up ...draw a V-bottom, then just below it, draw an identical V-bottom but extend the sides further up to match the original V-bottom's height (sorry - in a hurry or I'd draw it up).  The space between the 2 is the additional displacement.  If you just widen the chine flats, you only get a very little bit of extra displacement on either side of the boat...

Brian

BobC

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Re: BobC's build in Virginia
« Reply #11 on: January 15, 2016, 10:13:22 AM »
Things have more or less stalled out this week without much physical progress although I did manage to get into quite a debate over the chine build method over on the THT site where I have a build post.

For some reason the Fishyfish website is now on a blacklist with our company filter. I can only access it through my mobile.   Must be a snafu with the changes going on over there.  Perhaps our filter is confusing Phishing with Fishing.  LOL ;D

Anyways, I planned to get started on lofting/cutting the shelves this week but the slave cylinder on the truck tranny is shot and it won't move. I can't haul long materials or plywood in the car or on the wife's vehicle so I'm going to have to get the truck into the garage and tear the tranny out.  Delays, delays.  Always something.

 Contemplating milling them on site from logs with my bandsaw mill using clear Virginia Pine or possibly strip laminating them over a jig similar to the gunnels on a canoe using 1/2"X 1-1/2" Eastern red cedar which I also have a supply of and can mill .  The ERC is super light and air dried it can be a little brittle on its own but very strong when laminated. Seem like that would work well and I wouldn't have to buy or haul anything. 

Brian, Thanks for your great support and putting up with all my modification questions.  Sorry if I am being a pain.  Taking time to get see Oyster this weekend and get some pointers on epoxy/tape.  Held off on the seam taping until I am confident I have it right.  The salt air should get me refreshed and moving again... :)

starbright55

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Re: BobC's build in Virginia
« Reply #12 on: January 15, 2016, 11:08:26 AM »

For some reason the Fishyfish website is now on a blacklist with our company filter. I can only access it through my mobile.   Must be a snafu with the changes going on over there.  Perhaps our filter is confusing Phishing with Fishing.


If you haven't paid the $0.99 for the Tapatalk phone app, do it. Super easy to post pictures directly to the thread from your phone!

Question  (typed from my phone, so it will be brief ), on your reverse chines, are you doing the down angle all the way to the bow? I like the reverse angle idea and will probably incorporate it into my build but I was only thinking of doing it from amidships aft and was think there would be no need for relofting then.

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Ed Snyder

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Re: BobC's build in Virginia
« Reply #13 on: January 15, 2016, 09:49:04 PM »
At the firm I did my apprenticeship, all our hulls had the chines & spray rails swept down quite a bit at the outer edge and it kept a fair bit of water away from the cockpit - weather dependent, in rough weather no amount of chine shape helps!

To help, but does cost, the stop-sides can be left to sit higher than the chine flats (hull still on jig) and then hand plane the top side ply to a nice fair line (eye-balling it as you go) then fill with thickened epoxy, or cheaper, laminate strips of off-cut ply on the chine flats slightly lower than the finished desired chine then fill and long board sand her fair.
Try to get a straight line going aft though, as Brian has said, this can affect your ride if there's curves or humps.

Real easy to fill with micro balloons and long board sand - 3 ft long say 4 inch wide using say 1/2" ply or timber - keep the edge of long board off the hull side so as to not end up with a sanded grove you'll need to fill again later. And sand.....
Not waving....... Drowning!

starbright55

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Re: BobC's build in Virginia
« Reply #14 on: January 19, 2016, 05:13:16 PM »



If I re-loft the bottom panels to make the bottom panel assembly 2" wider, then this displaces more water (making the boat float higher) than if you just made the chine flats an inch wider on each side (which hardly displaces much additional water and has next to no impact on the waterline). 

How much higher do you think it would sit? From what I remember the chine is normally about 3" underwater at rest.

Now, I also remember something about longer GA's (say, 28'6) already sits higher than a 25' GA (or 24'6 in Bob's case). When you're maxing out length, do you still think the added waterline beam and displacement would work?

How about the fact that you'd have less dory flare - any negative on sea keeping ability?

You know,  between moving and that new job, etc, if you have time to reloft things,  let me know and I'll be your guinea pig!


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