Chine and bottom panels

We’ve made great progress this month, and as a re­sult the hull skin is now com­plete, save for a lot of fair­ing – but that’s for another month! Ben Meakins re­ports

Practical Boat Owner - - Contents -

The first fit!

Our Se­cret 20 was pretty stiff and un­yield­ing even be­fore we fit­ted any ply­wood sides, but with the sides, chines and bottom panels in place, noth­ing moves in the slight­est.

You may re­mem­ber that last month, we in­stalled the sup­port­ing struc­ture for the bottom panels – stringers and bow cheek pieces – so this month our job list started with fair­ing ev­ery­thing back, in­stalling ex­tra sup­ports where nec­es­sary, fine-tun­ing ev­ery­thing and in­stalling the panels. That might not sound like much, but it meant lots of plan­ing, scrib­ing of panels, cut­ting out and a great deal of epoxy work.

The first job was to fair back the struc­ture ready to ac­cept the hull panels be­fore in­stalling chine panels, fair­ing these back and in­stalling the bottom panels. The boat’s struc­ture – both lon­gi­tu­di­nal and trans­verse frames, with stringers added to sup­port the hull – forms a se­ries of box com­part­ments. Some of these will be­come lock­ers and oth­ers wa­ter­proof spa­ces.

TRIM­MING BACK THE SIDE PANELS

We had stuck the side panels on be­fore we turned the boat over, mak­ing sure the top edges were cor­rectly aligned and planed to the level of the deck stringers. How­ever, we’d left the lower edge over­sized so that we could sight along it and en­sure it made a smooth curve – much eas­ier done with the boat up­side down.

Boat duly turned, we could set to plan­ing it off. This was com­pli­cated slightly in that the edge had to be planed in a bevel to al­low the chine panels to sit flat upon the chine. We took the waste off with a Bosch elec­tric planer, which while it ap­pears to be a ter­ri­fy­ing, noisy ma­chine can be sur­pris­ingly del­i­cate if set cor­rectly. How­ever, for this job we set it to max­i­mum depth and took the an­gle off the side panels in this way. Half an hour and a lot of wood shav­ings later, the panels were planed to some­thing near their fi­nal shape.

The next step was to plane off any

wob­bles and fine-tune with a nice, long hand plane.

Us­ing a Stan­ley No5 plane, we could run it along the bev­elled chine stringers to plane down the edge of the ply­wood to match.

Glu­inG on ex­tra sup­ports at the bow

From the fourth frame aft, the hull has three faces – side, bottom and stringer – and each edge is well bonded. How­ever, fur­ther for­ward, the bottom panels butt up to the side panels and must present a smooth curve. This meant that we needed to glue in some ex­tra sup­ports to give the panels some strength.

We cut notches in the frames to ac­cept a piece of Dou­glas fir be­fore fit­ting it with tem­po­rary screws. To en­sure that we weren’t wast­ing ma­te­rial, or hav­ing to plane off huge amounts, we bent the tim­ber around the frames to match the hull’s curve. To do this, we used tem­po­rary screws on two of the three frames, but used some rope and a Span­ish wind­lass to pull the front edge in. This was re­mark­ably ef­fec­tive, and once bent to shape we could epoxy it in us­ing fil­lets.

With the mo­ment where we at­tached the bottom panels fast ap­proach­ing, we re­alised that it would be worth spend­ing some time in seal­ing up ar­eas that would be­come in­ac­ces­si­ble or sealed. With this in mind we painted out lock­ers and floata­tion cham­bers with epoxy, adding fil­lets and fill­ing voids in the con­struc­tion.

seal­inG in­ac­ce­si­ble voids and Gaps

WEST SYS­TEM had pro­vided us with a tube of their new Six10 prod­uct, which they say ‘com­bines the strength, re­li­a­bil­ity and ex­cel­lent phys­i­cal prop­er­ties of a two-part West Sys­tem epoxy with point-and-shoot con­ve­nience.’ It comes ready-thick­ened, and as such it’s supplied in a sealant-type tube, with a special noz­zle that mixes the two com­po­nents.

Ap­pli­ca­tion is as sim­ple as squeez­ing the trig­ger and point­ing the noz­zle. We used it to seal up a tricky area in the bow buoy­ancy tank, where a void ex­isted be­tween two tim­ber com­po­nents.

In con­sis­tency it’s like a sticky mi­crofi­bre mix, but was easy to ap­ply and didn’t run. We tried a few sam­ple fil­lets, which came out well – but as it has less filler in than you’d usu­ally use, you need to use more glue to achieve a good ra­dius. It is sticky enough to form a use­ful fil­let.

An elec­tric planer made short work of trim­ming hull sides back to stringer level

The hull sides with the correct bevel planed in to match the stringers

We glued in ex­tra tim­ber sup­ports for the bow panels, pulled into shape by a Span­ish wind­lass

ABOVE The Six10 epoxy came in a car­tridge with a mixer noz­zle LEFT This was good for seal­ing hard-to-ac­cess voids and gaps BELOW Our test fil­let proved good and strong when it had cured

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