Self building a sailable tender

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My inflatable tender is approaching end-of-life.

I could just buy another. But I have a dream of building a rigid tender from plywood and epoxy with glassed seams.

The criteria is that it could take a small outboard, or be rowed, or be sailed with a small lugsail that stows under a thwart somewhere.

Needs to be big enough to transport two adults on a choppy day. But light enough to drag up onto the pontoon on my own. And strong enough to take being dragged on and off a pontoon.

I'm thinking instead of a centerboard and housing perhaps it could get just enough lateral resistance from a pair of small bilge runners. Not trying to be a high performance racing dinghy.

The icing on the cake would be dinghy wheels somehow located amidships near the center of mass instead of the transom, for easy movement on land. But they must be removable or fold up so they're not in the water when you're underway.

Anyone know of any designs for such a craft?

Alternatively, please tell me all the reasons why this idea is ridiculous
 

Tranona

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There are loads of plans available for building such a boat example here from the sponsor of this forum keyassets.timeincuk.net/inspirewp/live/wp-content/uploads/sites/19/filebank/pbo_pup.pdf you can't avoid some sort of keel, usually a dagger board if you want it to sail, although lee boards are possible to avoid holes in the bottom. adding wheels sounds like an unnecessary complication that will add weight and reduce space. Having designed and built 2 epoxy clinker 8' prams the key issues are getting the right amount of rocker and balancing light weight with robustness. Be aware that it is more time consuming than you imagine if you start from scratch rather than buying a kit.

Watercraft magazine is a good resource for all things to do with designing and building small craft.
 

MisterBaxter

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Iain Oughtred if you want to build something beautiful like his 8' Auk or 10' Puffin designs; or Phil Bolger if you want something pragmatic and functional like his Nymph design or frankly brutalist like his Brick design.
(Bolger designed beautiful boats too but his small sailing tenders were functional rather than elegant...)
 
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B27

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I think you'll need a decent centreboard.
But otherwise, go for it.
Bearing in mind, it is actually quite a lot of work!
And the materials won't be cheap to do a nice job.

Tenders are there to get a hard life, I wouldn't want one too shiny personally.
 

MisterBaxter

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I built a Bolger Nymph years ago, it only took a few days. I didn't build the sailing rig, just used it as a rowing tender. The sailing version has a very simple leeboard which leaves the interior clear and is an order of magnitude quicker and simpler to build than a centreboard. From memory it only took two sheets of ply and some small-dimension softwood. He's a genius with frugality of materials and quick, simple construction.
 

MisterBaxter

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😻

thank you.

Building a tender is on my list for next year, not this - but thank you for introducing me to that one.
His designs are all just perfect to my eye. But I've never found the time to build anything really lovely like that, I've just knocked out a few utilitarian craft... But there's a beauty in function and economy too.
 

justanothersailboat

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His designs are all just perfect to my eye. But I've never found the time to build anything really lovely like that, I've just knocked out a few utilitarian craft... But there's a beauty in function and economy too.
There is, but I'm not going to get many chances...

I had been looking at some of the Fyne Boat Kits options. I think the Oughtreds have the edge but Fyne have some that are a bit simpler and some nice nesters. Decisions...
 

Sea Change

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I built a Spindrift 11N, from full size templates. No previous boatbuilding experience and it took me about three months of evenings and weekends whilst working full time. There were some very late evenings in there, though!

I've never weighed the whole thing but the basic dinghy+oars should be around 40-45kg. It splits in to two sections and nests on the foredeck. The rig came from a windsurf and is light and easy to handle. I've also got a bigger 'performance' rig that I rarely use, because it's too cumbersome. Under motor (3.5hp) it will sit at about 5.5kt, and 4kts is easily achievable under oars. We've done more than 7kt under sail, with the small rig.

It cost about £800 to build, most of which was the four sheets of Robbins 5.5mm ply, and the two big packs of epoxy.

It's been a brilliant project and being able to sail the tender ashore or around an anchorage just for fun is easily the best part of cruising for me. The boat is big and stable enough to go on pretty serious expeditions carrying up to six people under sail, or nine under motor.

11ft is pretty large, of course, which makes the boat a very useful daily load carrier, and far more stable than an 8ft dinghy would be.
 

William_H

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I built a Sabot sailing dinghy and used it as a tender. Rowed beautifully. I never really explored the sailing potential. However i would go for a standard centre board box and plate. Not hard to do.
Re wheels I have a 12ft ali dinghy as a tender with wheels standing up permanently attached at the transom. It is easy enough to invert the dinghy and pull by the bow. Easy to set up and I would suggest you try this option first. Just as an aside I have a 4 wheel mobility electric scooter (Shoprider) with tow hitch and tow the dinghy home up a hill. Works out well. ol'will
 

ridgy

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The Dix design above just uses stock aluminium tube for the mast and boom. The 8' is just two sheets of ply, no need to get robbed at Robbins. Very low cost.
 

rogerthebodger

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I have built several plywood tenders from using stich and tape as well as frame and chine but considers the possibility of using flat sheet GRP either stich and tape of over a frame then adding internal laminating but haven't got round to it as if yet
 

Minerva

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On the ply front - If you're laminating inside and out from GRP woven cloth from new, I presume marine ply would no longer be necessary? The trade off being a slightly heavier tender....?
 

B27

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On the ply front - If you're laminating inside and out from GRP woven cloth from new, I presume marine ply would no longer be necessary? The trade off being a slightly heavier tender....?
Unless the outer sheathing is quite thick, it's quite easy for it to get penetrated by a knock on the slipway or something.
Which would quickly destroy cheap plywood. Quite probably most marine plywood too?
And the heavier you build it, the harder it knocks on the slipway etc?
 

MisterBaxter

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I would say that metal strips on the bilge runners and stern corners are a good alternative to all-over epoxy/glass sheathing. Although both would be pretty bomb-proof...
 

SvenH

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Metal strips are hard to attach in a way so that there is no way for water to enter in to the wood.
If there is any way for water to reach the wood, it will eventually get there.

I make sure that any hole in the boat gets epoxied before connecting stuff, and screws are off limits. If "a screw" is the only way, it has to be screwed in to an epoxy plug.
 
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