Sail Life - DIY foam core carbon fiber dingy 

Hi Mads, happy to have you pick my brain any time you need as long as you promise to keep a log of your build hours. 😅 Really appreciate your praise and support. Russ. P.S I love whatsapp, typing is a pain!

Mads and Ava, my two cents for the next project boat - we've seen you do an "extensive refit" with major structural improvements and lots of oh glorious sanding. I'd watch you do that again on another boat if you really want to, but others do that too. What makes you different, IMO, is your software engineering approach, and your willingness to embrace every gizmo and gadget known to boating. I would really enjoy seeing you leverage what you've learned on Athena to do a keel-up "systems-based" approach to a refit. Analyze which gizmos worked and which didn't, and plan out how all the systems would ideally inter-operate - electronics, plumbing, HVAC, etc., and then optimize the refit to fully support those choices. I personally think that'd be interesting - curious if others agree or disagree.

A tip on your dingy models, don't forget to add some ballast on the back to stand in for your outboard motor and some cargo. It may take a nose dive now, but what happens when there's a scale outboard, Mads and Ava to balance it out?

Boat design! That's a fun project. Some tips for your design process of your dingy, you might already know all of this, but: when the draft changes on a boat, the position of center of buoyancy (COB) will also change. Not only vertically, but longitudinal. So depending on how deep your 3D printed model was seated in the water during your testing, you will get different trim results. Also, your model has a center of gravity (COG) entirely dependent by the filament of the 3d printer. If you test a scaled model, you need to add some heavy weight to shift the COG to the position corresponding of your full scaled boat. So currently your testing model has the wrong COG. To find COB in CAD: split the boat at the waterplane so you only have the underwater volume; the center of volume of the water displaced is the center of buoyancy. If your CAD software doesn't present the center of volume it will probably give you the center of mass of the displaced water, which is the same as center of volume since the entire model has a consistent density. To calculate the COG you need to multiply the position of each article with its mass. Then take the sum of that and divide with the total mass. Add as many articles as you can, including the fiberglass and foam core. Example of longitudinal center of gravity (measuring from the stern): Mads 85kg longitudinal position 900mm, Anchor and chain 12kg longitudinal position 1700mm, Engine 15kg longitudinal position 50mm. (85*900+12*1700+15*50)/(85+12+15) = 871mm for longitudinal COG. If your COG is on the same longitudinal position as the COB, your boat will be level. In this example it would be 871mm. After this stage you either shift your COG by moving equipment around. Or shift your COB as you did in the video.

Palm trees and polar bears 😂😂

"To make a long story short"... 😂 Mads, it's always interesting to hear your thought processes, even when they drag out a bit... 😉

On the dinghy. I’ve been designing a dinghy cause I don’t like how much work is required to keep a deflatable RIB floating, haha! I also don’t like the ride. Looking at your design I recommend not focusing on the OC dinghy. Take a look at old runabout boats of the 60s and 70s. They have bigger dead rises at the bow to help cut thru the waves yet they have rounder bows. If you study these older boats you will notice all kinds of cool features that are not on RIBs and the OCs. Hope this helps and gives you some other resources. One more thing, be sure to plan for an engine well. This in case water comes in from the low engine support. The old Boston whaler is always a good example except I don’t care for the low free board or top sides. Others are the Larson, Bowman, Century of the 60s. They are mostly designed with lakes in mind so take that into account.

Hi Mads, American Naval Architect who now lives in New Zealand after sailing here in 2009. Happy to have some back and forth a by email (phone is harder with time zones) to discuss dingy design considerations. Designed a custom alloy dingy when we got to NZ and have done all kinds of design from sailboats to high perf power cats to tugs and barges thru my career. Been watching since your early days with obelisk so happy to help.

Many people are learning about boating here and a minor correction will help them out. To calculate scope you take the distance from your anchor roller to the water, add the depth of water, add the maximum expected tide rise(or storm surge if applicable), and add the depth to which your anchor is expected to bury itself when anchoring in fluffy bottoms. Take that number and multiply by 7 for chain length. You can shorten in a crowded anchorage, but know that you are short scoped and take extra precautions. I think that people just using the current water depth is why so many people drag. The purpose of the bridle is to reduce shock loads and is one of the precautions you can take to avoid problems when short scoped, though we use it all the time. This means a stretchy rope, like the Mantus bridle. Dyneema does not stretch enough to be useful. This wasn’t an anchoring video, so no criticism is meant.

This is all quite awesome. So very cool you’ll take us along as you design and build Galloping Gerta!

Consider using a lee board that can be moved from one side to the other and stowed flat in a molded floor socket. Also consider a gaff rig, which can be stowed in the boat too. Besides freeing up storage space on Athena, being able to conveniently stow the sailing components in the dinghy keeps it handy for emergencies.

I’m so glad I had just swallowed my coffee for the “palm trees and polar bear” commentary or there would have been spray…😂😂😂😂

My Yamaha 4 from 80's was a two pull wonder until i donated it away. Amazing engine. Started better than me at 40 year of age :D

The OC and OneTenders are fantastic boats, all be it different designs and have both set the benchmarks very high. The OC hull design with its deep chine and flat section on the bottom of the v hull enables easy planning, good tight handling and stability at rest with heavy offset loads such as standing on the gunwales. One of my pet hates is a rising bow before you get onto the plane meaning you have to shift your weight to the front of the tender so having such a wide bow could affect this dramatically and not for the better? I would also put in a floor liner with additional foam underneath that will improve buoyancy for safety and give a flat bottom to the inside of the hull. This would be simple to do and not add too much weight and the benefits will outweigh the cons. I look forward to your project, best off luck.

Hi , your always full of great fun and ideas , that is freedom ? doing it your way and always asking ? Your point of balance is just over the next horizon . Keep your videos coming and we will see you there .😉👍

I built a ten foot nesting dinghy which takes up half the space.... obviously. Used carbon foam sandwich vacuum bagged it and yes it's a lot lighter.... and won't rot and with Kevlar on the keel so far has been very durable

As for dinghy design: If you prefer sailing, you should check out the seggerix - a stitch&glue plan which you could easily replicate by bending the foam core instead of wood and then lay-up the carbon. It also uses a windsurf rig which is readily available, fast, cheap and easy to store on board. The other option you might want to look at, if powerboating is more the reality, is the scowlike hull design of the boston whaler 110. It offers maximum space on that footprint, high stability and a lot drier ride than anticipated. Ultimately if all options: power, sail, dry ride, stability, weight, handling are non-negotiable, you should end up with something along the lines of a dabchick with 5-6 inches more freeboard and a windsurf rig. - one thing is for sure though: with that speed demon, you will be flyyyying.

Your enthusiasm is infectious!!

I made some thing very close to what you're thinking. Sandwich pvc foam, glass and carbon. Performs well. I can send you picks.

I know you are excited by this project but there are so many lightweight, stitch & glue plywood dinghies that would fit your needs. Have you ever seen Phil Bolger's "Bee" step-sharpie design. Really cool. Check it out :)

Hey Mads, let me know if you need help with Fusion. I recommend always having every single sketch fully defined. Otherwise it can mess up your project later on. Its a bit buggy without fixed sketches. Also I would model the hull paramettrically and as a solid block. And then use the shell tool to form the inside cavity later on.

Three things to make your hull cleaning easier and preserve your paint. 1. Get a 12 inch drywall knife. That 4” knife is useless. 2. Get glazier suction cups. Attach to your hull just above the waterline and you can reach 6 ft with your drywall knife without your hookah. Twice as fast. 3. Keep those pads away from your anti fouling paint. The drywall knife is all you need to reactive the paint rather than sanding it off.

I'd look at a long shaft conversion for your outboard. It might be an option. Having the nose a bit heavy is likely not a bad thing as the opposite has always been an issue. Dinghys used to be designed for rowing and hanging an outboard made them stern heavy. For speed look at some stepped hull designs. This may not be practical on such a short hull but works a treat on 7-8m boats. I hope a real designer can educate you on designing point of balance, roll correction and point of thrust. I remember some small boats that were fast as stink, 40 kts fast, but even a slight turn was scary and poor helmsmanship would flip the boat and coming off plane had to be considered very carefully to avoid being swamped by your own wake.

If there is anyone on RU-vid that can do it, you are the one! One idea for that semi flat bottom is to look at chines in the design. I am not a boat designer, but they would look pretty cool and I think help with “gripping” on your turns. Good luck!!

Can't wait to see the result on your dinghy project! You where lucky indeed with the immigration officers! It's a nightmare at any port on Tortola. They are not welcoming at all! We lived there for 10 years. If you need a dentist go to Premier Dental in Fish bay, they are great. If you need more info about the BVI (no s, it's IslandS, S already there ;-) shoot me a PM.

Hull shape ... twin hull or semi-displacement hull shape. The twin hull should give you more stability when getting on & off as the pivot point is closer to you while transferring on or off. Have a look at Zodiac or Avon inflatable hulls for that. Getting on plane isn't difficult as they usually require less hull on the water to do so. Balancing of the load - people, fuel tank, etc. - both fore and aft, and side to side will absolutely help. The semi-displacement hull will provide great stability at low speeds since more of the hull is in the water, and quicker on-plane condition at a lower speed, so long as the load is well balanced. My boat's hull is of the semi-displacement type, and she's been great in all the usual sea states. I should think that a dinghy with that style hull shape should also perform well.

Mads, I'd suggest considering a couple of steps moulded into the transom either side of the outboard well for climbing in and out perhaps with a moulded grab handle

Maybe a little more deadrise in the aft sections to take a bit of displacement out of there. But only a bit. You could probably get a way with the deadrise you have. Don't think you want to add more displacement forward because that will induce more slamming. Slope the sheerline (top of the boat) from forward to aft. Suddenly the boat will look like it's trimmed nicely while not doing anything about the underwater shape. For course stability a skeg will help. Your example dinghy has a skeg that is narrow forward and widens aft, but it's still a skeg that 'bites' in the water and helps for lateral resistance when you steer (without any lateral resistance the boat will be horrible to steer, like an inflatable without a rigid bottom). The widened skeg is also nice to help drag the dingy over sand without the wheels. With 15 hp and your flattish bottom planing should not be much of an issue I should think. For the bow, have a serious look at good RIB designs, they are still relatively pointy to prevent slamming and wave resistance when not on the plane. Your design will likely cause a serious bow wave at reduced speed, you don't want that either. And as with all designs; life is a compromise. You cannot get all aspects fully optimised, just optimise the aspects that you value most.

Mads - hopefully your CAD program gives you center of volume at various waterlines. I’ve forgotten how to scale weights, but it is definitely in line with scaling water volume. Your design should have been a little bow down to account for the motor, gas tank and you in the back. You need to account for at least you. (Maybe you’d sail without the motor or with the battery one.) Anyway at a given load and estimated dingy hull weight, you should be able to get a center of volume (buoyancy) and then work your design to where your weight centers and CB line up. (It’s been a long time since I’ve studied naval architecture and used it, but I’ll look up on my shelf and see if I can find you a book.)

It sounds like there are quite a lot of amateur sailors in the Caribbean, it's simply because you are a Viking Mads, we grew up with the sea and just know more about it and its environment. it must be pretty annoying to be surrounded by so many amateur sailors - It's great to see your approach to the weather analysis, because you're absolutely right, and it's all about knowledge and experience. After following you for a while (I'm an old sailor myself), it seems like you're almost the "only one" on YT who knows what you're doing, your approach and knowledge! Nice to see the worlds oldest Country flag on your boat. All the best from Denmark!

I had the opportunity to operate a carbon OC tender over a number of weeks and in varying conditions (fully loaded, unloaded, calm, choppy). We had a 2-stroke 15hp Yamaha OB on the transom and it was a blast...on plane almost instantly. However, the ride was incredibly stiff and had, what my butt determined, was zero flex. The coamings were great as steps for entry and exit but when sitting on them in anything but perfectly calm conditions it was tough on the tailbone. The lightweight, for the length/size, also makes it very lively in choppy conditions when compared to a similar size more traditional dinghy (even an aluminum hull RIB type) and this can make loading/unloading at the mothership more interesting. I certainly recommend thinking about how you might be able to increase the ride comfort a bit without sacrificing too much of the OC Tender design's good initial stability and overall sportiness. Also, carbon might have the cool factor but e-glass might be a better option due to its increased flexibility (and ability to withstand impacts with less damage).

Your projects keep me going. 👌

I know absolutely nothing about boat design, but I sure do enjoy your DIY vlogs. Looking forward to your next project whatever that is.

Before you completely dive into boat design consider doing a Stitch and Glue build. Aladino over at Sailing Magic Carpet built a tender this way and they seem very pleased with it.

Those specs pretty much apply to me as well. I’d be interested to make iteration of this dinghy. Light weight, simple, sailable and to fit into my dinghy garage. One option could be to cut CNC plug from cheap construction foam and go from there. I did one 3D-cut project for a rigid spray hood and it worked well! Maybe this could be an open source DIY-project? 😊

Hi Mads! I hardly recommend having a look at stitch&glue methods for the dingy (if you haven't done yet). Software-wise, a glimpse into Delftship Free or Freeship Plus (which is the somewhat further developed predecessor and might be slightly better in regards of import/export) might be good.

It was great seeing you in San Juan Airport. Maybe we can catch up again at the Annapolis Sailboat Show on October

I can't wait to see your tender build.

Thanks for the update Should be fun watching on the 3 d dingy build. Have safe sails ahead

The dingy build is gonna be awesome

Great update 2x👍 Looking forward to see the new dingy come together.

Designing and builder your own dingy is an ambitious project. Have fun with it!

Hey Mads, when I'm underwater or along the topsides I usr a window or glazier's hand clamp, gives you a positive hand hold. Cheers

Love the idea of a dinghy build can’t wait. Thank you for all the great videos.

YAY dinghy design. I hope you get a friend to partner with to make it just perfect for you and Ava! Hope her travels are going great!

The flat patch at the bottom of the dinghy is good thinking. It's called a pad. Add self-bailing qualities to your list. Scow-bow is another good idea, it adds internal volume to feel like it was a bigger boat as you go forward. To eliminate pounding you transition from 8-9° deadrise at the stern to 16-18° deadrise at the bow. The pad gives you a flat bottom when on plane that offers efficiency. I have an idea on how to make a cheap very strong foam core I've been playing with. I used it to make another type of structure start with Luan board (like a very thin ply). Epoxy 2 sides and edges, use it for an outer skin, then Luan again as an inner skin. Use 1"x1" spacers (maybe 1.25" high?) throughout every 12" in every direction to hold the 2 layers evenly and uniformly apart so there's a cavity between the 2 sheets. Now inject expanding urethane foam in between. The result will be very very strong and light. Layer of glass over the finished product. I am unsure about how you will hold the hull curvature and angle transitions, but this is the method I'd like to experiment with myself.

Oh glorious sail life ! Thanks mass

Awesome, as always!

We have an oc tender and love it. We will be in the bvi's in a week if you want to take another look. Take a look at the AS Tender for the rounded bow you're talking about.

18:13... Mads; Don't forget that when your outboard is on, then it will/should level out in the water. I'd also make my painter attachment/s low in the bow section, so that when it's towed it rides correctly. I think what, once you've cracked your transom height that you have a good design there.

Your model dinghy looks a lot like a Dyer Dhow 7'11" dinghy that is very common in New England but in other parts of the USA as well. You may want to take a look as it may give you some ideas for your project.

I use Freeship CAD software for hull models. It's a bit old school but the files MAY be compatible with your CAD software, and more importantly, the .part files for the layers are almost universal. The hydrostatics functions alone may make manually re-inputting data points (if necessary) into your Cad software for CNC worth it.

Nice idea, but there are lots of great off the shelf dinghies you can buy and be done with it tomorrow. Spend the next year sailing, not sanding. in the words of John Kretschmer: "don't let perfect get in the way of sailing"

great video

The stepped in transom is a winner! I had an Arima 16 footer which planed with small power due in part to the transom design.CHEERS FROM HERE!!!

Super excited about your upcoming dinghy project. Modeling is going to be very important to determining your final design. Dimensional scaling aside from obvious reasons, but when you build your model, ensure you scale the mass both longitudinally and laterally so you can see how it behaves in the water. Don’t forget to create scaled loads that you can move around within your hull to simulate weight distribution. You will have as much fun with the testing as you will with the actual build.

I would think the easiest way to find the hull shape you like would be to go test drive as many as you can, then copy the design of the one you like the best. Matt from Duracell just finished building his dingy and I bet her knows lots of builders and has many ideas.

Good video!

Wow... "Mr. Early Poster" this week. Good luck with the course. Please give some consideration to providing some content about your experience with the course. I may want to follow you in the future and try it myself. Your views on the process will help! Cheers, David

good epi and editing

I'm excited to see the next projects. Another dinghy for some inspiration might be the "Mantus Dinghy" She's a bit heavy but looks tough. Cheers

Really excited to see the tender build. There is a channel on RU-vid (which unfortunately is not posting regularly anymore) called RedBarnBoats which I used to watch religiously. If I remember correctly, he had some good videos on planning and testing out new designs. He would tank test using tiny cardboard models with weights to simulate people. His builds went into great detail from tank testing to sailing the finished boat. Slightly different builds methodology (stitch and glue using plywood) than what you are looking to do, but could be worth some of your time to look at one of his builds.

Consider putting in foam for floatation in the dinghy or water tight storage spaces that would serve as the same purpose.

An important design criteria is to optimize surface area in order to achieve maximum sanding surface.

I'm not experienced with hull design of power boats very much, but I'm a naval architect. From my point the bow you designed is way to voluminous,it will slow the boat down when hammering into the waves. Instead to achieve more volume under water sharpen the V forward so the bow will set into the waves more comfortable and smoother. At the same time the planing surface is rotated a bit which will lift the bow in planing mode and let the crew stay a little dryer.

You need to be looking at jetski hull rather than a dinghy. A ski uses a slight curve with a flat or concave centre and a series of vains on the outer. That will give you the desired ride characteristics you are looking for.

You might want to consider Basalt cloth as it is greener, cheaper and has better impact resistance than carbon. Would definitely go down the 2nd hand windsurf sail/mast/boom combination as others have suggested.

I like the t-shirt you are wearing, I just ordered one 🙂

I somewhat love the hull shape of the OC Tender but not the deck layout because the fuel tank should be located up in the bow but also it should have some type of lock box which the OC Tender is missing. I also prefer a V shaped bottom for choppy conditions. I do really like that bow design where it's V shaped but also the bow is vertical to hold the rub rail that I really love a lot. I'm not a fan of the rounded bow shape that you have designed and it wouldn't bother me a bit if you designed a boat with a long shaft. I'm OK with the wide rails to sit on but don't really thing that they need to be that wide. I love your idea about trying to copy the way that the OC Tender is build and Gone With the Winds has a great video of the process of one being built in the factory. I'm very much interested in possibly getting a set of plans from you because I'd also like to build one and have been thinking about a design myself because I can't afford to spend 20k on an OC Tender. Sail ROAM has an OC Tender 350 with a reinforced transom that Russel beefed up to support a 20 hp that I would definitely go with. They said that they are using half the amount of fuel with the 20 hp than they were getting with their 15 hp. That's a huge difference. The best way to make a mold would be to build ribs like you were talking about and then put 1/4" wood strips. Then sand smooth and you have a perfect mold. I would want to be able to use it as a sail boat, row boat and tender and I would get the OC Tender 350 size with the 20 hp. I'm not a fan of the dagger board pocket taking up space and wish there was a way to remove it when your not sailing. Not sure how to accomplish that but I'm sure it's possible. I guess it could be possible if you were to add a flat deck inside or a false deck to give it some lateral streingth and then install an extension base with additional top mounting points for when you use the daggerboard. Other than that, use a plug that is flush with the bottom of the hull to stop the water from coming in. I also want to build mine out of carbon fiber just like you explained. I'm planning on building a Cyber 48 and this would be my tender.

you should consider an electric scooter for travelling distances like you did in the taxi. At those prices, the scooter(s) would be a savings. They would also be great for just looking around.

I was anchored off Prickly Pear in some very big winds once on a power-cat and I will admit I got in closer than I probably should have because the windage on that boat was insane...and it walked like crazy. We held just fine, but no less than 3 other boats dragged, with one of them having no one wake and ended up somewhere between Leverick and Malone.

Have you considered maybe a hybrid style tri hull design? That may give you the stability, and plane action that you want?? While keeping CG low and the draft shallow. But that might generate a lot of parasitic drag in the sailing part of it though…

You should look to open fourtys and minitransats they have great planing abilities and they are great sailboats

If you need help with this come up with the CAD design and I can help make tooling in my CNC shop. I’m looking for a similar dingy for my own sail boat and want to use an electric outboard. We can figure out pre preg and layup. We can also cnc custom deck fittings and other items.

Very interested in your dinghy design project. Please keep us updated.

Mads, it you look at the OC, it has spray diverters, where the bottom transitions to the sides. They make for a waay dryer ride, when on plane. Best wishes to all.

Mads, I think it would be a smart idea to build a quarter scale version of your dinghy hull before you start committing to full size. while you certainly couldn’t do it with the 3-D printer you have you might be able to figure out a way to make all of the basic moulds in a 3-D printer with greater capacity, in sections. That’s gonna greatly accelerate your time if you want to make multiple versions. And your materials cost would probably be about 1/10 given that multiple criteria like the ability to survive a storm isn’t very important in a hydrodynamic model to judge buoyancy. If you look at what superfastmatt who’s got a car building channel is doing with moulding his car bodies and parts, you’ll see that he’s pretty fearless in making mould components out of multiple 3-D prints.

I think you might want to take another close look at the hull shape of the OC tender. It has these ridges on the sides, I think they're intended to ease getting the boat on plane by trapping some air under the boat. I think they also act as a bit of a keel to make the boat turn better.

You may consider looking at a tournament ski boat. Flat in the back, a "v" in the bow to cut through waves and turned down in the front to knock down spray. Ski Nautique would be a good place to start to see how they knock down the spray and cut through wakes...

Spiffy yammering on a Sunday 😊

I designed and built a dingy. Mostly based on what would fit in the foredeck. I named it “ Arrogant “. I was arrogant enough to think I could build a better dinghy lol. I have high hopes for your project. It has a chance

Check out the Johnson Skiff (old 14’ boat) and Ankona Boats in Florida. Very similar to what you want.

$40 each way 😂 Bro knows where the catch is. Great vid as always!

I would love to see all there is to learn with the dingy build (sadly though )I am far too poor to become a patron as much as I would love too so ill keep liking & sharing & hoping to see more 🤩❤

Your 2nd dinghy attempt was looking good, bar the high transom. Don't forget outboard weight and buoyancy projections either side of it, you don't want to be bow high. We stuck with Hypalon and a rigid hull - at 3m strangely enough, although air leaks are a pain. Your best bet is probably a straight copy of a proven design, don't reinvent the wheel!

The flat section on the bottom is a delta pad. You want one!

I am building a large new workshop this year but once its done, I really want to build a small boat. A catamaran with electric motor and solar panels.

Carbon fiber may be sexier in theory, but in order to get the weight savings and take advantage of the greater strength, you really need a mold to vacuum against. What you’ll end up with using moldless construction, is a boat that’s just as heavy as fiberglass with extra brittleness and overpriced fibers inside. Building a fiberglass over foam core boat will already be sufficiently lightweight compared to wood cored dinghies and have the benefit of being repairable at any port in the world. Fiberglass also handles minor impacts better than carbon. Also, the stiffness of carbon isn’t always a benefit. When pounding into waves, the greater elasticity of fiberglass is a feature that your butt and cargo will appreciate. If you simply must be fancy you can always add a layer of aramid (Kevlar) to the outer hull to improve abrasion and impact resistance. Aramid and fiberglass have similar modulus, so mixing them is fine. If you get cheeky and decide to use a layer of CF to cover a FG boat for aesthetic reasons,… don’t. Carbon has a much higher modulus and can cause structural failures if used to cover a fiberglass structure. The point is, disregard sexy, and really focus on appropriate material application.

Have you seen the AS Tender , similar to OS but with a more rounded bow , excited to see what you come up with ! Love your videos

The OC Dinghy´s advanced hull shape, is very much dictated by it´s aim at being a great sailboat as well. What you have designed Mads, is a speedboat. If you wish to properly sail the boat with a small rig, you need to put the sailing qualities (of a sailboat) at the forefront, when designing the hull shape, and adjust for the planing qualities afterwards. You will end up with something more similar to the OC Tender, just shorter, with a rounded bow.. Good luck

You are very brave

The OC has a flat spot on the stern bottom for one reason only... to fit a jet drive (that they offer as an option) If you don't need such a thing, the soft dead rise you show would be easier to build without the flat. Having a flat portion at the chine is quite common and the general rib design uses it's pontoons for this.... in fact the pontoons create a bit of a tunnel on either side to trap air and reduce friction while moving through the water.... of course it also helps with stability at dock. But rubber or vinyl is pretty heavy and the average soft boat of 9ft is 120lbs :P Even a solid plywood boat can do much better than that.

Can I say as being one to want to build the exact same thing with the same restraints. My mind has always gone to a tri-hull design. Food for thought.

Mads, you mentioned on one or two videos now about your next boat, any chance of a video on lessons learned from the current one and specifically what your looking for in the next one and what your considering during the decision making and Search process?

I would suggest a mix of materials. An used aluminum pontoon would be great and cheap. Then weld a bottom and keel on. For 3,000 budget you can have it welded and glass in the seats and extras. Delos has an aluminum dinghy and it never fails them. Well worth the money. Also you can run multiple 3" to 4" tapered keels down a john boat to help tracking. Bass pro has the prowler, a 12' john that 700.00. It might work? Love the show.

Might want to add a lip up front like jetski's and wake surfing boats employ to force spray outward when slowing from plane.

If you want to replicate the OC tender, take a look at Bolger Diablo, the under water sections are very similar, and it should be possible to make the stem more vertical with a foam carbon build. Just leave out the aft 4 feet of the hull, should be able to squeeze it to 9’.

look at a 319 stacer proline for inspiration. if you had any questions about if they turn watch the dinghy derby. stock class uses a 15hp yamaha.

I am very interested and excited to watch your dinghy build. I also expect to build a dinghy some time in my future. Unfortunately, I am not a boat designer.... but one design feature I am considering is a nesting dinghy. Have you considered this? I see the main advantage is more compact storage while on passage. Potential to increase the size. A lighter effective weight, as you only need to lift half the boat at a time.

I wouldn't worry to much if the 3d printed model is a little bow heavy. The weight of the outboard should compensate for at least some of that... Our Caribe 8ft dinghy also floats quite odd until you put the motor on... Thanks for the video by the way anf Cheers from Panama!