Coastal Cruiser

Hi Rick,

The most I am willing to go is for 6 - 7 meters, and although I do realise the restrictions put on only 7 meters, in that case I have to stay in the bay and local waters.

What are the differences, weight, speed , size from your design from your previous concept?. (hereunder attached) We both have some commitments in the next few weeks. Lets give it a rest and we chew it over. By that time everything should have been normalised here at the yard.

Fanie, although very much appreciated, a 10 meter long folding up Cat with seperate cabin is exceeding my limits I have set. You have sofar done a great job on your cat. Wish that everything is here so freely and quickly available. Unfortunately, Cape Town is for me the closest to shop for materials.

 

Mr Willoughby

I believe it probable that the design that Bert has posted (I'm assuming it is one of your concepts), and the yellow boat in post 37ish have the potential to have a 'cult' following. Lightweight, powered by the sun, wind, even a 4HP outboard, would be attractive to many people. This is not only environmentally sustainable but desirable.

I've been searching for materials for a project not related to boating and came across polypropylene honeycomb core sheeting. The density of the product with no skin is about 80kg/cubic meter. The cores are 8mm in diameter and a variety of skins can be 'welded' or bonded to it. Do you think a variant of this technology is realistic for this design? See Polycore for an Australian source.

Harry

 

Yes Harry, it is one of Rick's earlier design. I quite liked it and made a print out.
Bert

 

Hello Rick

Do you think that polypropylene honeycomb panels with 600 or 800gsm cloth bonded to the core could be a possible material for the construction of a boat of this design? The honeycomb cell diameter ranges from 8mm to 13mm. I believe the 8mm core weighs 80kg per cubic metre. The impact tests on www.polycore.com.au impress me.

Has anyone used this material to replace plywood for boat hulls? Here in Tasmania where plywood costs 5-7 times more than it does in the USA, it is possible that it might also be competitive in price.
Harry

 

I have used Klegecell. Corecell is highly regarded. I like the closed cell of these materials.

The layup and thickness of foam panels need to be specified to get the required panel strength. I expect something around 800gsm cloth on Corecell of the appropriate thickness and density would be be suitable for most areas. A bit light for waer areas.

Rick W

 

Rick
The last minute of the impact test video on the www.polycore.com.au site shows testing done with duracore foam. Foam has significantly less strength compared with PP honeycomb. I still need to confirm pricing but I think it will come in cheaper than the foam products.
Harry

 

Harry
That is impressive. It is no doubt worth a closer look. I would want to do my own testing and see how others are using it.

One problem I have with its use is actually making panels at home with honeycomb. I will ask if they are making preformed panels.

Once you get up around 800gsm cloth skins you have a panel that can take normal human point loads. Most of the structural stresses will be less than the stress from point loads on a small cruiser. You would want some beefing up in obvious collission points. It is common to have some crush zone with solid foam in these areas.

I will have more time next week to follow up.

Rick

 

Rick, I talked to some builders about honeycomb cores. The trick is to use a special (different) type of epoxy on the lamination against the honeycomb. This epoxy sometimes comes in sheets. Or, your prepreg supplier can provide you with prepreg with honeycomb suitable epoxy on one side, and a more typical laminating epoxy on the other.

Then, you just cook it, and the epoxy makes these beautiful perfect fillets into each honeycomb. As one builder described it, "Its using chemicals instead of workmanship to make that bond."

 

Harry started a new thread on the topic. Alik made some interesting comments about its use above the waterline.

I have worked with foam and seen the flat panels that can be bought from manufacturers in Australia.

Alik's comments put me off considering the honeycomb below the waterline.

Rick

 

Rick, why did you go with flat panels for the "pedal from Canada to Hawaii" boat? Isn't there a big performance penalty?

 

The boat is very close to the ideal shape for the constraints set. The below waterline of the hull is a bit more complex than it needs to be to get its current shape. The flat panel method evolved from discussions around build quality and weight control of a one-off boat. It was not my idea but I embraced it as the design progressed.

My V14 hull started out as a shape compromise with flat panel for ease of construction after the discussions on the ocean boat and experiencing the pain of building V11J using V11A as a male plug.

In the design phase V14 proved to have a very small performance penalty to go to flat panels. The difference according to Michlet was about 2% in favour of V11J at 12kph. As it turned out V14 is a better boat in all respects compared with V11J. Maybe not better in performance than CP2 (V11G) that GregK built because he got his very light but it was expensive to build. He also operated without a shaft strut for the record he set on CP2.

I get the impression there is much misunderstanding about hull lines. I feel water has less trouble negotiating a slight corner than most people think.

I believe a flat panel hull can be made superior to any curvy hull so it is not a compromise.

Rick W

 

I would be interested in your thoughts for the the use of this material for the 'yellow boat' design in post #37. The various panels could use thicker or thinner core material with the knowledge that each millimetre of thickness will add or reduce the mass by 0.08kg/square metre.

Without going ultra high tech (expensive) to keep the weight down for this design I reckon that the cost to build this design could be favorably reduced.

I know you are trying to achieve a coastal cruiser that is powered by wind/solar and I trust that you will achieve that goal. I too am interested in your goal. I believe however, that your work thus far (wind,solar,peddle power,hull efficiency) could assist many in the near future into a low budget camping style-coastal cruiser using a very small, light, and cheap to run 3-4hp outboard. The 'yellow boat' design looks perfect for this camper/cruiser. Is it?
Harry Tams

 

Harry
I agree that it can be built in glass and not affect performance too much.

I played a little with some arimid honeycomb and had great problems getting it sealed everywhere in a flat panel type construction. I did not use pre-impregnated cloth so that would have helped. Irrespective I believe the integrity is stuffed once the outer layer is breached. Water will get into the voids and "pump" the bond from inside. It will be somewhat like osmosis. I would suggest foam below the waterline but there is not much of that in area - maybe addition tough fabric in the layup.

It takes a lot of work to go from the yellow render to something that is economical to build, suits your needs and reliable/safe in operation. I am happy to take you down the path but you should find someone else to detail it. If you want to use the honeycomb then you should find someone experienced with its use. I would not use it on a major project without testing it on something small like a pedal boat or finding someone who has used it with confidence in the same way I intended to use it.

To get more serious you need to make a wish list of your requirements. Things like self-righting is important to me. I was relying on battery weight to guarantee this. More head room in the cabin will increase windage. These are the sort of things that need to be optimised for your needs.

I never got into an internal layout. It sort of lends itself to neat bunks but making room for stand-up shower in the cabin becomes more difficult.

You then need to home in on the weight. If you are serious about operation in the ocean I suggest you consider a little diesel saildrive as this helps with getting some useful weight down low and also the use of a decent prop. Not cheap and additional limitation for trailering. There may be other solutions. A typical 4HP outboard does not have suitable prop to give a boat with this windage serious weather capability. OK for getting about on a good day but not in bad weather. When I get an electric boat going it will have a prop around 600mm in diameter not 200 to 250mm.

It may be worth your while starting a new thread or just starting private emails with me. If you do not have Delftship you can download it and view the my files as you like. It would help working on layouts if you can view them in any orientation.

Space was very tight with the ocean pedal boat and I suggested Greg make mock ups so he could confirm adequacy. This has worked well for him. Even with the best 3D imaging I have seen some serious mistakes that walk-throughs did not pick up in plant design.

Once you get the basic shape and layout sorted it is then time to get a good NA involved who understands the construction materials you want to use and detail the design. I have proposed locations for internal structural bulkhheads as well that could constrain the internal layout. These are intended to avoid any other internal stiffening in the cabins. However it is iterative to get the best outcome.

The most important part is to have an idea of how much you want to spend. You can probably arrive at a reasonable estimate with a little research and not much cost.

Rick W

 

Rick, I am attracted to your original concept, that is similar to GregK's pedal to Hawaii boat. Even without standing headroom!

I've had an awful lot of fun on boats without standing headroom throughout. For example, standing up in a hatch works wonders.

A couple of weeks ago my wife and I were camping in Big Sur. A couple showed up with a very interesting camper: http://www.tinycamper.com/ It had no standing headroom, but it sure did work. The concept was: stand up when you are outside, and you are always right next to outside. The galley had a hatch that is opened, and then provides cover I guess, shade, and canvas sides can be added for windy days to keep the stove operable. It sure made a lot of sense! They had a lot of fun with that camper.

So imagine a boat that has no standing headroom anywhere, but has a hatch in the head: open the hatch to stand up, erect a tiny tent using the hatch to take a shower. No need for headroom over the berth, settee, dining table, helm seats, just arrange things so these are all next to the cockpit, so you can stand up as you walk to any of these things. Put the galley in the cockpit, with a bimini for times you are boating when you probably really should have stayed home.

This would dramatically shrink the required size of the boat: kinda like your first drawing on post #1 of this thread!

And perhaps it could be pushed around with a 4hp outboard: 0.4 gallons per hour flat out. OK, maybe 10HP, so the alternator is big enough to charge the house battery, still only one gallon per hour at full throttle.

Probably could be arbitrarily cheap too.

 

The faux-tri concept did not develop until Greg was well into the refinement stage of his ocean boat. He had spend a lot effort mocking things up. We went through a few iterations. He has demonstrated that he can live in it but the living is primitive. The boat requires quite a heavy keel for the stability he wants. It does not need to be as heavy for self-righting but they felt skittish with two of them moving about in it. A faux-tri could be made with more room and have enough form stability to feel secure without the heavy keel. With a bit of weight like batteries and motor down low it would be self righting. It would be a much easier driven boat.

The keel on Greg's boat is 1m deep. It cannot be beached without swimming. Not something you want in a trailerable boat. It is like an Etchells on the trailer.

Also note that I was glad I was not footing the bill for Greg's little boat. He has had some financial support from various sponsors with supply of gear free or at cost. To but it at normal retail makes it very expensive.

You and Harry need to get together and sort out what you would like in a low power cruiser. It seems you have similar goals. I am happy to play around with this concept and do performance predictions.

I have attached a rendering of my latest thoughts. This started out as a day boat but I have difficulty getting away from the need for a boat this light to be self-righting. It has room for 3 big solar panels (up to 230W each) on the cabin top and more panels could be placed along the sides. It will be less Darth Vadarish with windows and hatches. I have not completed the layout of the cockpit. It has stoop room inside the cabin. Room for bunks and small table etc in the cabin.

If you were going to use an outboard it would be best mounted in a well in the cockpit rather than hanging off the stern as it would be less prone to aerate.

Getting weight down low is important. With batteries it is easy. They are always there. With fuel it is a different matter. I also do not like the idea of flammable fuels (FP<38C) on boats. Diesel is OK.

My performance target with this one is 8kts at 600W. It would be less bothered by side windage than the yellow one.

Rick