Playing around with a 10 m trailer cruiser

[marshmat]

Just a little update here, now that moving's all done and I've got a bit of time to work on this project again. I'm starting work on a tow-test model, around 1/5 or 1/6 scale, to check out how this hull shape actually runs. Proper tank tests are out of the question, of course, but I'm working on a rig to tow it alongside Sunset Chaser which I think will give pretty decent results provided the lake is fairly calm. I'll keep you guys posted on how it goes.

[Willallison]

There have been a couple of good articles on tow model set ups in Proboat if you have access to them. Tom Lathrop (Tom28571) also has some good info on his website about the setup he used.

[longliner45]

hey marshmat ,,in novembers sailing mag ,there is a 40 ft trailor sailer ,made by scott minclintock of az ,,he says he launches it at the ramp,sorry I cant post a pic ,but maybe someone can,,,longliner

[marshmat]

Thanks for the tips guys
I've read Tom Lathrop's article and I will probably use a similar bridle configuration to the one he designed for the Bluejacket tests. It does seem substantially more realistic than towing from the bow, although probably not as good as a true yacht dynamometer (waaaay too pricey for this!).
The test model is being built at 1/6 scale, making it 1.667 m long. No, this is not an arbitrary decision; mathematical simulations were done to confirm that the relevant dimensionless groups will be reasonably well matched over the entire speed range under study. Matching Froude number between model and prototype, the main concern in the speed range I am considering is that significant laminar flow may occur on the bow sections of the model (Re=5E5 occurs at around 21 cm aft of entry on the model at 10 knots scale speed). Suggestions on how best to account for laminar flow effects on the model (since there is virtually no laminar flow on the real boat) are welcome. I'm looking into mathematical ways of correcting for it; roughening the surface is an option albeit probably not a desirable one.
Some snapshots of the model under construction are below. Nothing's fixed in place yet but I couldn't resist the temptation to just slide a few bulkheads onto the strongback to see how it looked..... more snaps coming soon with bulkheads fixed in and keel mounted.

[Willallison]

Glad you cleaned your workshop up 1st, Matt!

[SAQuestor]

Originally Posted by Willallison

Glad you cleaned your workshop up 1st, Matt!

I know all y'all go back a long ways together and all, but boy, I am sure glad I wasn't the only one to notice that spiffy workbench.

[marshmat]

When a workbench is in such condition, it is easier to simply call it "storage space" than to endure the futile battle to maintain order

my last trailer boat

[SAQuestor]

Originally Posted by marshmat

When a workbench is in such condition, it is easier to simply call it "storage space" than to endure the futile battle to maintain order

Good advice that I'll remember when SWMBO says something about my "workbench"

[fcfc]

Originally Posted by lazeyjack

my last trailer boat

This one is also trailerable. (it is the same boat, shown on different trailers at different stage of the construction).

http://www.bymnews.com/photos/albums...a_DSCN0742.jpg
http://www.ocea-yacht.fr/images/bate.../photo13_1.jpg

It just depends on what trailerable mean for you.

[Willallison]

Bloody lovely boat, that.

I like a person who adhears strictly to the less is more principal!

[marshmat]

How long did you have that one, lazeyjack? Looks like a good, solid build and practical design... what the working fishermen across from the yacht clubs call a "real boat". Got any more pix on ya?

It just depends on what trailerable mean for you.

Gotta love those pics fcfc The 14-axle boat trailer... what will they think of next?
*****
Update on the project- my towing test model is coming along well, just trying to track down some appropriate strips of wood for the outer skin (it's darn near impossible to get anything smaller than a 1x2 in the normal lumberyards, so I'm hunting down other local suppliers for the 1/8" strips I need). Hoping to get some numbers before the end of the summer. In the meantime, the ongoing repair/upgrade work on the existing runabout takes priority of course- rule of thumb, the highest priority is always to keep the boat that actually works in top condition The model's being slotted into whatever time is left.

built it for a farmer, he never touched it in 10 yrs so I,m putting the engine in, doing the interior, there are some pics in will trailer thread, but will post here too
she is very deep fine entry, huge girdars 400mm deep run full length, carries 550l fuel, but the disp will be higher now as he bought the D6 Volvo, weighs 750 kg with leg

you can see the wide chines, pretty essential for getting the boat planing and holding the plane at lower speeds and getting the tracking right downweather, I dont put on strakes , as they make the ride hard,
i,m trying to get the design from Rhino and Solid into freeship, but no luck yet, and takers to advise

[marshmat]

Hi all,
I know it's been a while since the last update.... things have been a bit busy here.
Got a chance recently to do a few more sketches on this one. Layout concepts and a few more profile sketches (yes, that's a Duoprop on the top one). Sorry about the lousy scan quality; image scanning for the moment consists of putting the drawing on the floor and pointing the digital camera at it, then bumping the contrast way up.
The first profile sketch is a more open design and matches with the general arrangement sketch shown. A canvas enclosure would be put up in bad weather. The layout drawn has the head down under the helm (there's good sitting headroom but no standing up in there); the two side benches would fold out into a transverse double berth at anchor. There's no dinette in this one; since this boat would usually see shore stops several times a day, perhaps the extra space would be better left open (the boat will also be expected to ferry lots of gear and crew around now and then). Small folding tables like those on a passenger train could be added to the bench ends.
Another profile idea (at bottom) is with a fully enclosed deckhouse, with the retractable hardtop (a la Mercedes SLK, right? ) and a raised deck over the forward cabin to improve headroom there.
On a semi-related note, I'm working through Dave Gerr's scantling guide (in Elements of Boat Strength) as a starting point for the structure.
Finding wood and time to finish planking the tow model is taking a while, so I'm not sure that'll happen this season. There's still plenty of time, of course, since the keel wouldn't be laid for some years yet.