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Nesting dinghy as a tender- decisions, decisions!


Aphers

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Hi

next year my family of three will be setting off for a few years of liveaboard cruising, aiming for an Atlantic circuit.

Our yacht has a babystay, limiting deck space to 2m max- and a bit less if we want easy access to the windlass. We have davits which we'll use for overnight stowage but not for serious passagemaking. I think a nesting dinghy is the best way to use the available space.

 

Our tender will need to primarily be a practical utility boat, capable of carrying three people and some shopping. I expect to use the outboard most of the time. A decent turn of speed under motor, even if only when lightly loaded, would be useful. It should be light enough that we can drag it up a beach, and sturdy enough to cope with daily use.

 

Having said all that, I am a sucker for a pretty boat that sails well (we learned to sail in a Wayfarer), and so I am leaning towards a Spindrift 11N. Good performance under oars would also be a big plus, as that is the main problem with our current rollup Avon.

 

I don't want the dinghy project to take up too much time/effort/budget, but I'm not afraid of a bit of a challenge if the end result is worth it. I know that a Catspaw would probably be easier, and there are various other pram plans around, but none of them really float my boat as much as the Spindrift.

 

So if I'm aiming for rough-and-ready, what's a realistic build time for the 11N? I've seen figures of between 40 and 120 hours quoted, but I guess everybody is working to a different standard of finish. I'm also really interested in going down the composite route- @ForthBridge's build is certainly food for thought. I live in a pretty remote part of Scotland so it might actually be easier to source composites than good quality marine ply, as the smaller sheets are easier to deliver.

 

I don't expect to be starting the build until around October, as my 'workshop' is actually a holiday cottage which will be occupied until then. It will be great having a big space at room temperature and be able to do epoxy work in the depths of winter. I haven't told the wife about this part of the plan yet :D 

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I went with the Spindrift 9N and have rowed it with 4 adults, (none of us especially large) and a few items. I followed the plans exactly and included the sailing rig. I loved sailing it around the harbors we visited with a cold one in hand and just enjoying the view. It tows well too.  I can't imagine 40 hours for a sailing version, and I am an experienced marine carpenter. I have no advice on using composites. I completely covered the gunwales in fendering, expensive, but worth it when a tender. I don't understand why one would think a Catspaw would be easier to build. It would carry a slightly larger load per foot, but sacrifice rowing and sailing ease in the process.  Both are viable choices. You are definitely on the right track and your parameters are sound.  My last comment concerns building.  Enjoy the build as much as you think you will enjoy using it.

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Thanks for that Dave, encouraging words. I wonder if I could get by with a slightly smaller boat, maybe the 10N instead. I can leave that decision until later of course.

At the moment I'm investigating different material options. Locally available 'marine' ply would cost around £180 but might be very heavy- twice the weight of Okoume ply. I don't think I can get Okoume locally, my nearest stockist is about £290 but would be an overnight road trip to collect.

If I go down the composites route, my choices seem to be PET foam, or Nidaplast honeycomb, in either 5mm or 10mm. These all work out cheaper and lighter than Okoume, until you factor in the epoxy/glass.

 

As a tender that will see daily use, I think it will be necessary to fully sheath the hull anyway. So the question is, how much additional glass/epoxy would I end up using over a composite core?

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Hi Aphers,

 

Having designed both boats that you are discussing I thought that I would give you my 10 cents worth.

 

I would definitely go with the Spindrift, the 10 or 11 will do everything that you want, but in a small loaded boat there is no substitute for a large footprint on the water if you can handle the extra weight. The 11 definitely has that. Having said that, I cruised full time for 10 years with a standard Catspaw 8 happily doing the job. It was okume ply with no glass sheathing. We were not large people and there was only two of us most of the time. She lasted for another 15 years after coming ashore. We loaned it to a lady who lived aboard, she lost it in a hurricane. It had a very hard life, always left out in the weather and had very little maintenance. That said she was a the end of her life when lost, it was no great loss. The 11 will be better motoring especially with a load.

 

What I learned from that is that sheathing is not necessary providing that you have good strong gunwales and fendering. The keel had a metal strip and metal under the chines amidships which allowed me to drag the boat up a concrete ramp or over the edge of a dock by myself without hurting the boat. The lack of sheathing did not contribute to her demise.

 

I like composite construction and both cores will do the job. With all materials thicker is better, as the core is light, it makes sense to choose the thicker 10mm versus 5mm core. Unfortunately there is not enough clearance in the sides to nest. The good news is that 5mm core with 10oz. glass on either side is stiff enough for the sides. The bottom core should be 10mm and will not interfere with nesting. There is a small issue to solve with using different core thicknesses which is where the chines near the bow are in plane.giving you a 5mm step to address.  With foam, it is easy to just sand the bottom to suit. Nidaplast is an interesting core but you cannot shape or thin it. Because this is hidden behind the forward flotation compartment, it would not have to be pretty. You could do a taper with thickened epoxy when you are ready to glass the inside where the step should be. A 5mm core bottom could be stiffened with stringers but that would be more time consuming and be less efficient than the 10mm core.

 

If using foam and you wanted to use 10mm core for the whole boat and you are up for a challenge, you could grind some foam away from the sides behind the nesting bulkheads to allow the bow section to have enough clearance to nest. The problem with cutting the boat before glassing both sides is that the hull will change shape and will not stay fair. I would still use laminated wood gunwales on a composite boat because it can take more abuse. I say that after seeing many gunwales rotted out because he fendering kept them wet. The trick is to use pressure treated wood. I do not know what it is called in Scotland but I am sure that it is available in some form.

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For what it's worth, I've been keeping a loose log of the time spent on my Catspaw build, and I'm up to about 110 hours. I still have fairing and painting and a few small details to go. This is working on it in bits and pieces here and there, which is not an efficient way to get the job done. Also, this is my first boat although I have some experience with wood-working. So unless you have some expertise, larger blocks of time, or are just faster than I am, I'd plan on spending something close to the higher end of your estimate.

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Thanks again for the very useful comments and advice.

I'm quite amazed to hear that an unsheathed boat made from 6mm ply could have a 25 year service life. Not what I would have expected at all.

I hadn't considered that using a 10mm core would interfere with the nesting ability- obvious when it is pointed out. I would actually be able to store the boat un-nested on deck, one half in front of the babystay and one aft of it. I have plenty of deck space, it's just divided into lots of little bits! Perhaps making the boat in two parts, but not nesting, would open up some options, like a thicker core, or a different seating/buoyancy arrangement in the aft section. It does seem a shame to throw away the nesting ability, though.

 

I will have to do some ringing around local suppliers to see what is available to me, but from what I can find online there is a huge variance in quality. Some 6mm Okume ply is only 3 ply, I presume I want to go for 5 if I can get it? The weights per m2 seem to vary a lot as well. I'm not sure if it's as simple as heavier=better, certainly I don't want to add weight to the finished product.

 

A total newbie comment here: I'm quite surprised at the quantity of epoxy that goes into one of these boats- the BoM for the 11N suggests up to 23 litres, which must comprise a significant portion of the finished weight of the boat. At UK prices this looks like the single biggest chunk of the budget too, although again there is probably more research I can do here to find lower prices.

 

As several other people seem to have done, I will likely be adapting a rig from a Laser or similar, both to reduce costs and build time.

One other aspect of the build that I haven't looked into yet is fendering. A string of small sausage fenders is probably about as easy as it gets, but not very elegant. It would be interesting to see what other people have found to work.

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I used no sheathing.  My boat weighs 70 lbs. Imperial without the sailing rig.  I used a solid bronze keel chafing strip.  I have barely worn the paint on the bottom in 6 years of active use and a few more casual years. Weight is the enemy for a tender. I wish I had built a 10, but never really lost any sleep over it.  Yeah, bigger is better if you have the room. I fendered my gunwales in one 20 foot piece of continuous foam filled canvas and then cut it at the nesting seam.  It wrapped around the transom by 8" at both corners.  I couldn't bump into my mother ship with anything but the fendering if I tried.  Make sure your row locks clear the fendering if you go this route or the oars will lift out of the socket when you row.  Guess how I know this?  ? 

 

I am away travelling for another 2 months, so I can't post pictures till I get my stuff out of storage.

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I built a Spindrift 10n to use as a tender on a pretty small J/24 for cruises from Marina del Rey to Catalina in Los Angeles, California, so no long distance voyages. The nice thing about a nesting dinghy compared to a Zodiac or other inflatable is how fast you are ready to go when you arrive at your location. While I usually have help dropping each half overboard, I've have done it by myself a few times as well. I hop in and join the two halves while in the water- I built mine so that there are no holes below the water line- it connects with two stainless steel brackets I designed. I also put a metal keel strip on so I could drag it onto rocky beaches.

 

As for sailing, I simply re-used my old Laser rig, which is very similiar to the plans anyway. If you build it with a Laser rig in mind you can save a huge amount of time, especially if sailing it will be just for fun. I love how the Spindrift motors as well as rows- I go much farther than I ever did in the old 9' roll up Zodiac. I have a 6hp Tohatsu which is the outboard for both the J/24 as well as the Spindrift and I'm very pleased with its performance on the Spindrift.

 

It's also the coolest looking boat at the dinghy dock, you'll always get a lot of questions about it. Thanks to Graham for designing such an amazing little boat.

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10 hours ago, Starboard said:

 I love how the Spindrift motors as well as rows- I go much farther than I ever did in the old 9' roll up Zodiac. I have a 6hp Tohatsu which is the outboard for both the J/24 as well as the Spindrift and I'm very pleased with its performance on the Spindrift.

 

Quite interested in this aspect- I'm not in any way a petrol head, but sometimes it's extremely handy to be able to get somewhere quickly!

6hp is about double what the Spindrift 10 is rated for... how does it cope with this, is it gnarly at all, and what sorts of speeds do you achieve?

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I don't really know what the top speed is- I haven't really pushed it. I probably putter along at 6-7 knots. And with the high thrust prop I have on it for the J/24 I doubt it would get on a plane. Keep in mind the Tohatsu 6hp is identical to the 4hp except for the carburetor, which has a slightly wider throttle. My motor started as a 4hp but I upgraded to a 6hp throttle. At lower RPMs the performance is pretty much the same. Previously I've powered the Spindrift with a 2 stroke 3.5 Nissan made by Tohatsu and a 2 stroke 5hp Mariner, also made by Tohatsu. They were also used on my J/24 but were a little underpowered for that use in adverse currents, etc. so I upsized a little bit. I liked them power wise on the Spindrift except for the 3.5 which had no neutral setting- it was pull and go. Made for some exciting launches from the dinghy dock.

 

One issue while motoring is water splashing in through the daggerboard slot. I cut a piece of unused foam from a camera case to fit perfectly in the top of the slot and that took care of the splashing.

 

Next time I take the Spindrift out with the 6hp I'll bring my old waterskis and see if I can get up- that would be a very worthy photo on this forum!

 

This photo is the Spindrift hauled up on a deserted rocky beach while exploring Catalina. That pretty much sums up why I built the boat.

 

catalina.jpg

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  • 3 weeks later...

I've been trying to track down a Laser as a donor for rig and foils- I'm sure if I wait long enough something will come up.

Presumably some similar dinghies would also suit as donors- Europe? Byte? There are Toppers everywhere but I guess the sail area is a bit too small.

It would be interesting to hear about people's experiences in using rig and foils from other dinghies, as I'm sure some will work much better than others.

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Aphers, are you trying to save money or time? I get that some don't want the hassle of building a mast.  If that were me I would find an old mast, maybe from a Laser, cut it down and buy the spec sail from B&B or have it made locally.  The plans give the sail specs as well. B&B sailboats designs are extremely well balanced.  I am not afraid to modify, but I never modify the hull or rig. I paid someone better than me to do that work.

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  • 2 weeks later...
On 2/22/2020 at 9:45 PM, Hirilonde said:

Aphers, are you trying to save money or time? I get that some don't want the hassle of building a mast.  If that were me I would find an old mast, maybe from a Laser, cut it down and buy the spec sail from B&B or have it made locally.  The plans give the sail specs as well. B&B sailboats designs are extremely well balanced.  I am not afraid to modify, but I never modify the hull or rig. I paid someone better than me to do that work.

 

Partly time/effort, partly money.

I need this boat to be my main 'daily driver', as a tender to a bigger boat- the sailing capabilities are a bonus. I could follow the herd and get a RIB of course, but there's various reasons why I want to go down the Spindrift path instead.

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The reason I ask these questions isn't because I need, or necessarily even want an answer.  They are questions I ask of myself to help in making such decisions.  My only recommendation now that you have answered is to use your answer to help you come to a conclusion.  If a balanced sailing rig is secondary, and it was for me, I still could not live with anything except the best available rig.  No matter how seldom I sail, it must be well, or my rendition of well, what ever that is. You have to weigh your requirements against the resources available and the costs of them.  Now that I have completely confused you, good luck deciding  ?

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If you're still trying to track down a Laser rig I'd go where the Lasers are- maybe a sailing club, yacht club or the like. I got my the Laser spars I have from someone at the yacht club who had an extra rig. For very cheap too. I often see old Lasers posted online around here that are pretty much complete including an old rig for around $200. The hull might be trashed but the spars look just fine. A brand new sail can be had very inexpensively if you buy a non-official sail from Intensity or one of the other 'practice' sailmakers.

 

FYI the difference between the full size rig and the smaller Radial rig is the bottom section of the mast- it's about 60cm shorter more or less, so even if all you can find is a full size rig it can very easily be cut down the the smaller Radial size. The top section and boom are the same.

 

Good luck finding the rig.

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  • 7 months later...

Getting pretty close to decision time on this project.

 

I've having some doubts about whether the 11N will fit on my foredeck (athwartships between mast and babystay, so nice and out of the way of everything). The 10N definitely will The new website drawings showing nested dimensions are really helpful.

If I had a cross section of the boat half way along the stern section, i.e. the middle of the nested package, I would know for sure whether it will fit the space. I don't suppose such a drawing exists, because it isn't at a bulkhead, but perhaps a kind soul could measure their 11N and let me know?

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