Learning CAD for boat design

From little acorns big trees grow. As a relative newcomer to the CAD scene, I began with a particular boat in mind. An upgrade project to follow on from the wooden runabout I already made during the first pandemic lock down. The idea had already formed by December 2019 and stemmed from a couple of pencil sketches and a small solid scale model. 

Now I need to elaborate on an upgrade with cleaner lines and a more speedy little boat that may also be build in my small garage.

Sketches may be drawn to very precise scale, formed into solid components and rendered to provide a quite realistic impression.  Also useful is the facility to view in-depth from a variety of perspectives

Not difficult to find drawing programmes for the laptop,  which vary in complexity from the simplistic to the baffling and complex. At the upper end of the scale some are available to the student or sole user-hobbyist for free, and I opted for Fusion360. It has an educational version ideal for the sketching of a small boat. The program incorporates guidance for the beginner which is useful and I found Youtube videos very helpful as well -  a few by boat builders, others by professional designers

Spray rails and a 17deg deadrise enable early planing

Sophia 11 :     Note the forward canted windscreen

 

Little boats = More exciting

 Settled fine and warm weather enable this little craft to be enjoyed to the full and what a blast it is on the water. 20 knots feels quite fast enough.  The first video shows me and Andrew planing along the coast from Teignmouth to the Parson & Clerk stack of red sandstone and along the exposed rail line that is hving to be strengthened at Dawlish by loads of ugly concrete walls. The engineering of which is quite inferior to Brunel's original masonry. At intervals of approximately 20 feet the use of rubber expansion inserts have been used all along the wall so far built. Those rubber inserts are already degraded and hanging loose all along the wall where recent storms have hit.

 

And the next video is taken the same week at Babbacombe where the crowded beach is being enjoyed .

Soon I am off to Brixham and across Torbay past the Arcadia and Queen Victoria liners moored up and polluting the atmosphere and emptied of the bow tie brigade and cocktail gowned guests.
 

And here is where the lunch box sandwiches and coffee flask are emptied. Beneath us there are plenty of Bass and Mullet swimming in the harbour.

And the very next day Matthew and I are Bass fishing and enjoying the little cove just south of Dawlish known as Shell Cove. Its only here that one is able to find the little Cowry shells sometimes used as necklaces or wristlets. 

Seals were basking on the rocks near here

Landing on the deserted beach and looking for some shade - but there was none.

Still waters edge this deserted cove

30 degrees or more of heat - It was here that a yacht carrying illegal immigrants was found in distress only eighteen months ago.  The crew are now serving time in prison.

Woody Runabout - Sea Trial

 With two well built crew this little craft performs beyond expectations with it's 20 hp Honda outboard (4 stroke).

The youtube video here was taken in Labrador Bay, South Devon where there are a several cruise liners anchored with zero passengers and nowhere to go.

The sea state was only slightly choppy and with a gentle ground swell. The wind was light and the run shows us about two miles offshore, between The Ness and The Oar Stone. Just around the headland is Torbay, Torquay and Brixham.

Woody Runabout Phase 21

Tired of waiting for my local wood supplier to dig out some Sycamore I chose to look further afield. Within easy reach (45 miles up the A303) I discovered Yandles wood merchants (Link) tool shop and craft centre. Not only was their self selection department open, the variety of woods is amazing and the prices significantly lower than I have been used to paying in Exeter.

I came away having spent more cash than I needed to complete the boat. Some too good to overlook that will come in handy for later projects. The Sycamore plank freshly cut from the tree is complete with waney edges. The creamy white texture is easily worked and will soon take on a golden honey colour, once varnished and exposed to the light.

The gunnels are in place, plugged with dowels into the holes that were the ones made by screwing temporary fixings, while the epoxy glue set. The epoxy was thickened to make it adhere better to the vertical surfaces. Also attended to is the motor well edges that have the lovely white contrasting wood enhance the appearance of this design.  A cosmetic indulgence to spend so much time at this stage.
The  35 fixing dowels/plugs whittled down individually and laborious but satisfying.

Now using Abranet, an open abrasive fabric that does not clog like sandpaper does.  I do recommend  it to any woodworker. Also recommended is diamond abrasive sharpening stones that put a keen edge on steel with the minimum of effort.

On the to do list :....  fit windscreen and cleats (after the deck is varnished) . Box in the batteries and switch gear. Run control cables through rear bulkhead. Fit seal to base of motor well.  Fabricate and fit front seat backrests. Fit support rails to road trailer. 

Grey tinted screen dry fitted to be supported each side by an additional pair of knees

Woody Runabout phase 16

One of several mistakes made during construction (yet to be rectified) was the inadvertent use of a waxy sanding sealer on the side panels. The adhesion is poor and I shall probably have to re varnish. The lesson: ALWAYS READ THE LABEL. I  discovered the error when using gaffa tape to hold a few slivers of wood where the frames meet the gunnels. On removal of the tape a patch of bare wood was revealed minus the varnish!   I intend leaving the job until autumn.  The wax base will need to be removed with a solvent and vigorous sanding.

The floor  is laid and incorporates sealed flotation chambers between the frames, now being painted before completion of the decking, fore-deck and transom decking.  The outboard unavailable till June because of the Covid-19 epidemic, as is the interruption to wood supplies which threatens to slow up progress.

In advance of decking, there have been fixing points for cleats added, and also fixing points for screw down straps that will secure the fuel tank and battery. Remote controls for the outboard run either side down the gunnels, and I am pondering the idea of inserting some PvC pipework to contain it, so as to make insertion and removal simpler to do. Putting such ideas down helps in the decision making and yes, I think I need ponder no more, just do it!

Unexpected problems always arise in scratch built projects such as this, and solving them becomes part of the enjoyment of brain teasing, burning of the midnight oil. One of them is how best to arrange the seating. Two seats, three or four, and should the rear one(s) face forward, sideways or rearwards, The best solution I am presently considering is to have the rear pair of seats facing inwards, facing each other so that weight would then be into the centre and away from the stern. So far, only one of the seat backs has been fabricated, in the form of an an ellipsoid hoop that I intend to make fold forwards. Laced with supportive Dyneema paracord. Sounds like one of granddad's lash up bodges, or it might just be some artistic licence and definitely unique. 

Woody Runabout stage 14

 Pressing on with the topside. The deck layout can be seen in the rough stages of fitting the carlins and deck beams. The cut out transom with very little freeboard, but relieved by the fitting of an inner transom and outboard well in between the two.
I have settled for the idea of having a false floor of 5mm ply;  easier to bale out and may even be self baling if the waterline is not too high.

The inner transom will be faced with ply infil tp provide a flotation chamber and motor well

Woody Runabout Phase 12

15th April and well under way with veneering the side panels with Mahogany - more like paper hanging than woodworking - done with the help of a razor plane and scalpel,  glueing on the ply with Instant impact adhesive. No second chances to adjust fit.
I shall be sealing with Luberon Sanding Sealer prior to applying varnish. Turning right side up will hopefully take place towards the end of this month (April).

Veneered starboard side panel

Port side veneer almost completed

Silky smooth finish ready to be sanding sealed

Transom now cut down for outboard with fifteen inch depth

Varnishing should take about ten days before turning right side up

WoodyRunabout Phase 11

3rd April sees me preparing the underside for painting an Ivory colour and ready to veneer the side panels with Mahogany, prior to laying on Epiphanes varnish.
The gunnels are fitted ,but will require additional layers once the woodshop re-opens.
The gunnels are glued and pegged with bamboo pins, avoiding screws in all but high stress areas, such as the prow and transom. I shall use screws for fixing the thwarts and dashboard because these need to be removable. 

Transom marked for the  cutout in way of the outboard motor.

Bottom panels prepared with Pre-Coat white base

Gunnels glued and pegged in position

Spray rails and keel ready for the plastic keel bands

Woody Phase 10 & design process !

Nearing the stage of turning right side up but potentially delaying due to limited access to woodshop and certain other materials during pandemic lockdown. ..

The skinning of the bottom and side panels is now virtually complete. I have to glue on the transom outer ply facing and will be ready to begin surface finishing and painting the underside. The side panels may be clad in Mahogany veneer but still undecided upon which glue and method of application to use. 

Almost ready to turn right side up

Transom ready for the outer skin of 5mm ply.

Sketch shows side tank flotation chambers but this feature will be omitted in favour of a false floor cockpit which should be self draining

Lightweight seating to be steam bent, laced frames, mounted  on cussion pads.

Doodle sketches

1/8th scale model shows outboard moter well, in front of the transom.

Underside shows chine, but the mould stations have been erased at this point.

Cockpit space open to variation but intention is to add two thwarts for mounting the seats onto. False floor not shown here.