Center line on Solid Hull

[papercut]

Hey guys,

 

I'm doing a MS Sultana build and following Chuck's practicum as well as hopeful's very detailed build log. However, neither seem to quite describe the process in which one draws a center line. This is what I have gathered so far:

1. The center line should be determined prior to applying the templates, as you match the templates to the center line

2. I recall a while back in one of the posts that a divider is used to determine the center line, but I can no longer find that post anymore

 

I'm thinking to use a ruler/divider to take center points across the deck and do a best linear fit with a ruler after the points are taken. But what about the underside of the hull, particular at the bow and stern? I'm thinking maybe using a flexible ruler as a straightedge, but it seems that could get pretty messy.

 

Any input is appreciated!

Edited July 15, 2014 by papercut

[rcmdrvr]

I am also a newbie.  I also have purchased the Sultana and have been reading the practicum.  I went to Amazon and noticed you can purchase a center ruler to assist in marking the centerline of the upper deck.  As for the bottom, I think I would make a platform with two right angle rulers to press up against each side and then use the center ruler to measure between the right angle uprights (If that make sense).

 

I want to add a question.  The practicum calls for quite a bit of sculpting the solid hull with knifes, files and sandpaper.  How do you guys hold a hull while doing this.  A vise?  What kind of protection do you use to keep from damaging the hull.  I have a good size workbench vise and have heard you can buy some leather covers for the sides of the vice.

 

Any help would be appreciated.

Edited July 16, 2014 by rcmdrvr

[BareHook]

I'm currently doing a similar solid hull build. I measured a center width near the bow and stern on the deck surface and connected the two points, this became the master center for the hull. for the bottom, I placed the hull with the deck down and marked the deck center at each end and projected it along where the keel will be, this is where you need to "eyeball: it and do your best at keep the hull level when upside-down. It may help to mark an array of dots where you feel you can locate the center and work you way from there. Hull carving can be done with a dremel or bench sander and or a curved xacto blade, just be careful no to take too much off, though worst case you can add filler to low spots since the hull is painted. On my kit I decided to plank over the solid hull, so its more forgiving than getting the shape dead-on.

 

Ken

[russ]

For holding the hull, you take a piece of scrap wood and screw it into the deck with a couple of screws. Then, mount the hull in your vise upside down with the wood block in the vise jaws. Later, the wood block is removed and the screw holes can be filled. Since the deck is planked, no one will see the holes or the fillers.

 

Russ

[papercut]

Center ruler! How interesting. Thanks guys. I can probably just use a normal ruler and do the math myself. I'll give the suggestions a try.

[grsjax]

Just my experience.  Most pre-carved hulls have enough extra wood in the keel and bulwark areas that an exact center line isn't really necessary.  Mark a point at the bow and stern that is as close as you can eyeball to the center and project this line long the deck and keel/stem/stern post.  As long as you are careful to make the line straight and use it as a baseline for the carving it should turn out ok.

[trippwj]

To do the Harriet Lane, starting with the hull downside up, I used calipers at each station to get the widths, then marked the midpoint off the rule. A bit of eyeball guided adjustment to align at bow and stern and drew the line.

[dgbot]

On a couple of solid hull kits I have run them through a bandsaw right down the middle. After pegging I would then glue the halves together with wood glue. This left a perfect center line.

David B

[BareHook]

David B,

The bandsaw idea reminds me of one way I thought of to convert a solid hull to POB. Mark your bulkhead positions and just slice them out like a loaf of bread. With the centerline cut and bonded, it would be easy the create the keel slots and the keel could be cut from stock material using the plans.

 

Ken

[grsjax]

The band saw ideas are very interesting.  You could cut both length wise and across and have a grid pattern to work from.  I would think you would need to make patterns the thickness of your saw kerf to keep the hull same size.  That way you wouldn't need to make templates for hull shaping.

[BareHook]

Re-bond them with thin stock to correct for the saw blade width.

[rcmdrvr]

Wow.  Somehow sawing in half seem like an "extreme" way to establish the centerline.  My bandsaw blade tends to wander, that would be a problem.

[dgbot]

Not really some modelers will cut the hull down the centerline then shape each seperately before putting it back together.

David B