Planning to build a sailing dinghy / tender

[Owly055]

    My recent thread about the Hobie Mirage Drive morphed into a dinghy thread, and I'd like to go further in that vein.   It is my intention to build a dinghy / tender with stitch and glue construction this winter / spring.  The challenge of course is that a decent sailing dinghy needs to have reasonable length, and of course a decent tender also needs some volume, which can be either length or width.   Finding a place to stow a decent size dinghy on a small sailboat can be a challenge.    The sailboat I've set my sights on is the Searunner 31, and I've worked out some solutions to the junk rig conversion on it.......not a simple undertaking.  There really is only one reasonable mast location, and that is just forward of the main forward bulkhead, and offset 8-10 inches to one side so as not to obstruct access to the dressing room area.  The offset should have no significant impact on the sailing of the boat where it's a trimaran.  This is mitigated further by the fact that the junk rig will have more balance area than typical, basically as much as I can get away with and still have the sail weathercock when the sheets are released.
     The mast location, further aft than I would like, and lack of any headsail or standing rigging, means that the foredeck can easily store a dinghy up to around 8', it could also be tied down between the struts on one side or the other.   8 foot or close to it, is about as short a boat as it's practical to sail, and as the dinghy will be "life dinghy", making it in two pieces isn't practical.
     There are many sets of plans for dinghies built using stitch and glue in this size range.  The simplest are flat bottom with a V bow.  A blunt bow on this style adds some interior space at the cost of one additional panel in construction.   The 7'10" Cats Paw by B&B offers a V bottom and a blunt bow, one more piece, two more joints.  The Bolger Nymph and it's deriviatives uses a double chine, a three piece bottom instead of one or two.   
     I don't know what the merits in terms of directional stability, and roll stability of these various layouts are, not being a marine architect.  The V bottom would seem to be the best in both respects.
     Then there is the issue of centerboard, leeboard, etc.   Leeboards would seem the least nuisance, but a centerboard trunk in an 8' dinghy should not be too onerous.   I recently ran across the concept of chine runners........... and I like it.    Much like bilge keels, on a sailing dinghy, chine runners would "bite" when heeled without the sailor having to do anything, and yet could be designed not to effect draft at all.   This is a concept most people seem not familiar with.   Here is a brief piece on them: 

http://www.piano-tuning.co.uk/microcruisers-and-the-chine-runner-concept/

The optimal "life dinghy", would have a high freeboard, and a compact size, pram design for max space, and sail well.    It would be enclosable with a weather cover.  Chine runners might well be the solution to making it sail well without a lot of leeway.

                                                           H.W.

[Owly055]

The Amazing Matt Layden      http://www.microcruising.com/pictures.htm

It's worth reading about this guy and his microcruisers, one as small as 8' which he sailed hundreds of miles.   The stand out feature of his work is the chine runner.   In one case he built a centerboard on one of his boats, and the next boat he dispensed with it, as it didn't provide enough additional windward performance to justify itself.  One feature of some of these types of boats is having the mast stepped further aft than would be expected, and using an oversize rudder such that the rudder itself contributed to lateral resistance significantly.   Below is a photo of his Enigma, 8 foot microcruiser on the beach, where the chine runners can easily be seen.   I love this kind of unconventional thinking!!   The chine runner and the bilge keel are somewhat related concepts, and the draft of the boat has a significant effect on the effectiveness of chine runners.  This suggests that a double chine with a slightly exaggerated chine runner might be worth thinking about, as it would tend to place the chine runners deeper more quickly than would otherwise be the case.    As I recall, toe in on bilge keels makes a big difference in their effectiveness, and this could well apply to chine runners, and dictate the shape of the hull panels for max effectiveness.   Interesting stuff to me at least, but I'm very tech oriented.

                                                                                      H.W.

[Frank]

Matt has been at it for a very long time. Extremely good sailor and 'out of the box' thinker.

[lastgreatgeneration]

I saw a video on the James Baldwin website, I think it was one of the cats paw models. However, I think I'm going to buy a used walker bay with a sail kit and call it a day. I have seen many of them and I'm impressed with the durability. Although they aren't that stable. Benefits: being easy to scrape/scour bottom without damaging gelcoat/epoxy/wood. Lots for sale on the used market at excellent prices. Although I still might make a plywood dinghy someday.

[CharlieJ]

Having met both James and Matt, I'd say you can't go wrong with either

Matt was at Sail Oklahoma when his Paradox, built by my friend Leslie Henson was sailed. She was nervous talking about the build in front of the designer, ,but when he sailed it he claimed-"couldn't do better myself" I've followed his designs for several years on Little Cruiser.

Had spent a day with James and his wife at his house ( she's a lovely lady) and spent the afternoon discussing sailing, and boats. Sharp dude.

[Owly055]

     Choosing a hull form is a bit of a challenge.   The most stable hull form for a small dinghy is a more or less flat bottom it would seem, but also the most subject to pounding.   A shallow V hull ,  appears to be the easiest alternative to a more or less flat hull, and a multi chine hull adds another piece and two more seams.  The Cat's Paw versus the Bolger Nymph would be the latter two.   Plywood only curves easily along one axis at a time, and that kind of governs what you can do as far as shape.
      I consider the ability to be sailed decently to be a significant priority.   The bow needs to be able to ride up and over waves, and ideally to cut through them, but due to the short length, the blunt pram type bow is almost a given.   It should be reasonably high, and the sides need enough freeboard that you don't take on water easily, but not so much of either that windage becomes a problem.   How much V and how much sheer?   In a boat that's about 54" wide, and under 8' long there are some limitations.  Front deck area designed to shed water, and narrow side decks to prevent entry when heeled over would be nice, but would add weight, and reduce space somewhat........but how much?   I could see a small front deck area, necessary for the mast partners, made with an inverted shallow V shape and a short combing along the aft edge, made into a water tight compartment, and 4 to 6 inches of side deck.   Some of the racing dinghies sort of fit the model such as the one pictured below, though it is much larger and heavier.  The task of selecting a design is complicated by many things, not the least of which is weight.  Everything added, adds weight.  It has to be light enough to handle easily, and small enough to stow.

                                                       H.W.

[Owly055]

     I'm on the verge of ordering a set of B&B Cats Paw 8' sailing dinghy plans... the two piece design.   I've been sourcing materials locally.   I plan to build a scale model first to get a good feel for it using model airplane type materials.  With 1/4" marine plywood at $42 per sheet (fir), this should be a fairly economical project, the epoxy and fiberglass tape will end up exceeding the cost of the wood I suspect, I'll probably order from Jamestown distributors.   Any opinions as to various brands of epoxy and weather bias tape is more desirable.   I expect the entire project including hardware, oars, mast, and sail, even if I do things on the cheap, to exceed $500 pretty easily, but that's still well within a reasonable range.   
     This by the way will be my first junk rig sailboat;-)

                                                H.W.

[Lars]

I use these guys exclusively for supplies.. they seem to have everything and certainly have great prices    check the 635 epoxy resin system

http://www.uscomposites.com/epoxy.html

[CharlieJ]

on my last five boat builds, I've used materials from B and B. Prices for epoxy is quite reasonable as are the tapes and  they have all the hardware for all of Graham's designs.

Call and talk to Carla

Do be aware that fir ply really should be sheathed with a light glass cloth, or it is prone to checking. Okume does not have that problem.

[Owly055]

     Thanks for the information........... I plan to seal the ply with epoxy, so I don't know that the checking issue is under the circumstances.  I was informed that fir checked, and luan was subject to rotting, and Okume was the optimal $95 per sheet locally.  The local fir is 3 ply........ I really want five ply and would prefer sliced veneer to lathe cut veneer ply.... I worked in a plywood mill years ago, so I know a bit about it.  The difference between $42 3 ply fir and $ 95 Okume is trival in the big picture.
     Jamestown distributors has better prices on epoxy than what I see at Us Composites website.  They have Total Boat and West Systems epoxies, and I have used West Systems before with excellent results.   

    The price just keeps climbing.  I'm not willing to motor freight materials in like plywood. Epoxy and glass is another matter.    B&B doesn't offer a kit for this boat, but their kit prices begin to look more reasonable.   I'm stuck with the choice of Okume at $95 and 3 ply fir at $ 42, and I'm willing to pay the premium of $159 for 5ply okume, as a one time investment.   

     I've found over the years that sourcing from one source can save money simply in freight.  The wood will be local in spite of the premium price, because I can pick it up nearby.   I'll try to source the big stuff (plywood and lumber) locally.  I live in a very remote area, and try to gather everything else into just one or two orders so the freight doesn't eat me alive.

                                                        H.W.

[CharlieJ]

I do not think a  coat of epoxy will prevent checking in fir ply..


After building some 25 boats in the last 20 years (for myself and customers) I advise new builders to think about this- The SINGLE most expensive thing you spend in building a boat, is your time. You can never get that  back. So use the best materials you can get. Then when you look at your finished product, you won't feel- gee, I wish I had used better stuff.

[Lars]

I built 2 boats in my life.. one decked kayak and a rowing tender. I will not build another. Boat building should be done for the joy of the build. I see no practical reason for building a boat other than that

[Owly055]

I do not think a  coat of epoxy will prevent checking in fir ply..


After building some 25 boats in the last 20 years (for myself and customers) I advise new builders to think about this- The SINGLE most expensive thing you spend in building a boat, is your time. You can never get that  back. So use the best materials you can get. Then when you look at your finished product, you won't feel- gee, I wish I had used better stuff.

     I fundamentally agree with your point.... hence I lean heavily toward the 5 ply Okume, the premium amounts to only about $150 for the boat, which is trivial in the scheme of things.    It is worth considering the fact that dinghies are stolen all the time in some cruising areas, so the question of weather to build cheap and expect it to be expendable, or to take other measures to make it a less attractive target should be considered.   In this case I lean heavily toward the latter.   A blunt bow pram dinghy without and outboard would not seem to be a prime target.   Distinctive customized appearance that is structural, the lack of an outboard, and an outwardly shabby look.  Good solid security, a built in location to cable it to a tree, or whatever, oars that cannot easily be stolen.   A homebuilt 8' sailing & rowing pram is not likely to be an attractive target for thieves like an inflatable with a nice 4 cycle outboard, or a stamped out Walker Bay with an outboard that looks like a million other Walker Bay dinghies.
    Back in the mid 70's I built a very expensive 3 speed bicycle using a high dollar racing bike frame.   It didn't say Gershatti anywhere, it had been painted over by the previous owner who was fleeing the law on a drug charge.... so I bought it cheap.   The crude bomb can red with runs in it made the bike look like junk, but I put many hundreds of dollars of the very best components in it, but used a 3 speed rear hub with a coaster brake.   From the expensive Italian made hubs, bottom bracket, crank arms, headset gooseneck, single front brake, to the titanium seat post and handle bars, to the beautiful leather Brooks Pro saddle, and even the pedals themselves, no expense was spared.  It was a $600 bicycle when the popular 10 speeds and 15 speeds were in the $150 to $300 range, but it was ugly and strange, and I never had to lock it in a city where 10 speeds were stolen all the time.   I used to park it among the fancy chrome bedecked 10 speeds, all chained to the rack at the university, and study nearby.   Hundreds of people would walk by, some stopping to admire this or that bicycle, and maybe once a day, somebody would notice it and do a double take because they knew bicycles.  It was a joy to ride, light and nimble, no derailers grinding away to shift gears, no caliper brakes except the single Campaginolo front brake which never gave any trouble, and which I rarely used because of the coaster brake.  The best bicycle I ever owned, and it belongs to my ex wife, who loved it as much as I did.  I don't  begrudge her the bike.........I chose to leave it and many other things.   A good woman, but not a good match for me.
     I want a dinghy like that bike..........

                                                                             H.W.

[cap-couillon]

Hard to find a dink small enough for the fore deck of the Solitaire so I built one out of Okume. Actually built two, one @ 6' and one at 7'-6" as it takes a sheet and a half for one so one extra sheet will build another dink. Sold the larger in a single day for the cost of the combined materials including oars and locks for both.

The design is by Hannu Vartiala (lots of freebies on his site) and based on a Portuguese fishing boat style.

Glass tape, fillers, and epoxy from Raka in Ft Pierce, Fl. Excellent products, great prices, and the phone is answered by a human being.

Finished 6' ways less than 50 lbs and while a bit tender in rough water, it rows wells. Re-enforced the transom for maybe a 2hp some day.  You can see the partially finished 7-6 in the background.

[Owly055]

     I like the idea of building two......but I'm not much of a craftsman when it comes to wood.   I'm opting for the 8' (slightly under) dinghy because I want a sailable dinghy, and the pram design for additional space.  It will take 3 sheets.  I'm also opting for the nesting version as it will give me the option of easily storing it on the foredeck without taking up a lot of space, though it should be easy to carry on one side of the Searunner 31.   Thanks for the Raka link.  I want a dinghy that has some recreational value also, and hope to recruit my friends two young sons into the project of building and sailing it before I get the actual cruising boat.

                                    H.W.

Hard to find a dink small enough for the fore deck of the Solitaire so I built one out of Okume. Actually built two, one @ 6' and one at 7'-6" as it takes a sheet and a half for one so one extra sheet will build another dink. Sold the larger in a single day for the cost of the combined materials including oars and locks for both.

The design is by Hannu Vartiala (lots of freebies on his site) and based on a Portuguese fishing boat style.

Glass tape, fillers, and epoxy from Raka in Ft Pierce, Fl. Excellent products, great prices, and the phone is answered by a human being.

Finished 6' ways less than 50 lbs and while a bit tender in rough water, it rows wells. Re-enforced the transom for maybe a 2hp some day.  You can see the partially finished 7-6 in the background.

[cap-couillon]

Most of the "stitch and glue" designs don't take a lot of advanced skills... just patience and attention to detail. Here is a link to a small gallery detailing the construction of my two, just in case you or anyone else following along is interested.  The build was lots of fun, and I wouldn't mind doing a few more designs just because. Learned a heck of a lot on the first go around.

Really like Raka... The hardener for their epoxy is all cross compatible and all at 2:1 ratio so no pumps. Fast, slow, and tropical hardeners may be blended to suit weather conditions. Eg: half fast and half slow for those early days of spring. Available as kits or individual components. 3Qt kit is about $60. 3" woven tape (6 or 9 oz.) $25 for a 50yd roll. All the fillers (graphite, silica, micro balloons, etc) are about 25% of the West System prices. Packed in bulk but quality materials. 50/50 mix of wood flour and micro balloons works good for  interior fillets at the interior hull joints.

Good luck and have fun... Post photos please.

[CharlieJ]

Here's a link to a five part article i did for Duckworks Mag on building a dinghy. It's a B and B Minipaw. 6'6"

The James and Rachel referred to are our own W00dy and Ralay, currently wintering in St Micheals Maryland aboard their Westsail 32 Mona.

http://www.duckworksmagazine.com/13/projects/dinghy2/index1.htm#.WH1eqn3NHUF

[Owly055]

     Thanks for the links!   Someone elsewhere posted a link to the " elegant punt "............... which is anything but.  One of the Dynamite Payson "instant boats", it's a quick and dirty design using lumber and plywood, no stitch and blue, external chines, and almost model airplane construction.  The bottom is covered with fiberglass cloth, the framing on the transoms is external, and of course it's flat bottom.   It uses a single lee board......... about as "quick and dirty" as it gets, but I'm still set on the two paws 8, though I would like to move both the centerboard and the split forward by about a foot to allow for "features".    That could prove a bit of a challenge, and would require a temporary piece.  Moving the centerboard forward compensates for the balance area of the junk rig sail I want to put on it as well.   The junk rig has balance area forward of the mast.
     I have ideas of experimenting with a couple of sail designs, and what better platform than a dinghy....... minimal cost and time.
                                                                  H.W.

[Godot]

It's been a few years since I've done any boatbuilding (16' Stevenson Weekender gaffer, 18' multi-chine canoe, and an 'Apple Pie' dinghy).

In all cases I used Raka epoxy with good results. Again, it's been some years so I don't know how the price compares to others now-a-days; but the results were great. I particularly liked their no-blush hardener.

[CharlieJ]

Over the years, I've used WEST (  many many gallons), Raka, Sys 3, MAAS, and the stuff B and B yacht designs handles.

Started with WEST in 1976

Had decent luck with all except one batch of Sys 3 which had bad hardener, and wouldn't cure. A new can of hardener fixed that.

The 2-1 mixes are all pretty much comparable, but I've found take longer to cure in cool weather than the 5--1 from West. Just a point

One point-  I have switched totally to   the B and B epoxy. Done 7 or 8 boats with it- I can get a gallon and a half (gal resin 1/2 gal hardener) delivered to my shop  for about what a gallon of WEST resin costs, without the hardener.

Haven't used any of the Duckworks epoxy  but Chuck is a friend, and I'd trust anything he sells. Just haven't needed any yet :)

Oh and the Amine blush thing is pretty much a non issue. Either recoat before it hard cures,, or do a quick wipe down with a wet rag and a bucket of water- it's totally water soluble . I do that as a matter of course anyway, if the epoxy has cured to a sandable state