Christer's planning-to-build-a boat-at-some-point thread

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Christer
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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by Christer »

piperdown wrote: Thu Nov 15, 2018 7:25 am There's also, according to the website, a cuddy cabin version.
Why not just ask them if it can be scaled by 10%?
I sent them an email asking the following:

1. Can the boat be built from plywood/fibreglass composite, using Okume BS1088 marine plywood?
2. Can the design be scaled to get a bit larger boat? I’d really like a 25-28’ length boat with a beam of 9.5-10’. My mooring berth is just over 11’ wide (340cm), so a 10’ wide boat will fit with a bit of care when docking. Trailering isn’t a concern, it’s not going to be trailered for long distances and there are oversize permits readily available.
3. Can the targa arch be moved back slightly and have a hardtop roof like the cuddy version?
4. Are the hulls deep enough to accommodate a stand-up head if put under the port console?
5. What is the tunnel height/bridgedeck clearance when at rest? I’ve been told that 400mm is minimum for a 22’ cat, otherwise wave slamming will be a problem. If less then 400mm, can the tunnel height be increased by increasing the height of the sponsons?

Haven't heard anything back yet, but time zone differences etc. We'll see. In any case I'm not in a hurry to start building anything big as my housing situation is a bit unstable at the moment.


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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by Christer »

jacquesmm wrote: Thu Nov 15, 2018 1:54 pm More questions came by email but I want to reply on the forum. Discussions on the forum will help hundreds of readers.

Christers asked about elimination or reducing the size of a cross beam in order to add bow rider style seating forward of the console as in the Hankinson design.
It is not possible.
One of the big differences between the Hankinson and the CT22 is the height of the deck between the hulls (bridge deck). His deck is very low. This provides volume to have a cockpit forward with seating and an enclosed head. That low clearance produces bad slamming under the deck. It can be acceptable for a protected waters boat used with the same program than a pontoon boat. It is unsafe offshore. You can see that very low clearance in the pictures posted above in this thread.
The CT22 has much more bridge deck clearance but it does not leave enough volume to have such a cockpit.
Look at the perspective drawings:
Image
See the box just in front of the console. That is the cross beam we are discussing, the one with a lid.
In the front, the height inside that box is about 6" above the bridge deck!!!
There is no way to bring that down or eliminate it.
Look at the hatches in the foredeck. Those compartments are 17" deep stern side and 10" bow side. That does not leave enough room for seats.

The choice is simple: have a low bridge deck (Hankinson) and lots of comfort but pay a price in blue water ability or have a seaworthy high bridge deck but no extra room for seating.
Anyway, I would never want to sit there in a formed sea, you"ll fly over board.

Seaworthiness or comfort.
That are your choices. It is not an unusual choice, compromises are a major factor in boat design.
The Hankinson and my CT22 are each good designs but for a different program.

The VT650 is another compromise. From what I see, the freeboard is higher, the windage is more than what I like. The bridge deck is lower but not as low as theWild Cat.
That compromise produces enough volume for the bow rider seating but there will be some slamming. Less than with the Wild Cat, more than the CT22.
Thanks for your reply, Jacques. Even if it's not what I wanted to hear, I appreciate it.

However, I don't want to eliminate the connecting cross beams, I understand they have to be there. Please don't take this the wrong way, but why were they/the box put there and not forther forward? By having it where it is, about half the usable space in the boat is taken up by the front deck and the box.

I quite obviously have no NA experience nor experience in designing a boat, which is why every time I ask something I feel retarded. I'm trying to understand why things are done they way they are, but this one continues to puzzle me.

I assume the low height of the forward lockers is because of the sloping of the tunnel ceiling, and that is also why the connecting frame box is placed where it is. Couldn't the front part of the slope be steeper and thus deeper, allowing more internal depth in the cockpit, and possibly also allowing the connecting frame box to moved forward?

With my stated program, I think either of the cats mentioned in the thread could work. I really want to build a CT22, but the way it's laid out, it just doesn't work for me.

I also realize that a standard monohull would be faster and a lot cheaper to build and given the right design, would satisfy all my requirements except being a catamaran. I'm going to have to give this some more serious thinking.
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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by Christer »

fallguy1000 wrote: Thu Nov 15, 2018 8:18 pm Here is a boat that is interesting. Not sure I get the bottom design.

http://www.spirainternational.com/study/ValdezStudy.pdf
Don't like how it looks and the framing scares me.
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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by Christer »

jacquesmm wrote: Fri Nov 16, 2018 7:47 am Please don't build a Spira. Many of his boats are made with 2x4's, panels don't bend, difficult to build.
I'm not planning to, he's got exactly 0 boats that I like. Plus, as I wrote in the previous post, the framing scares me. It looks like someone started building a house, then changed the shape of it and tossed it in the water.
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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by fallguy1000 »

jacquesmm wrote: Fri Nov 16, 2018 4:12 pm
fallguy1000 wrote: Fri Nov 16, 2018 8:14 am
I was hoping you'd critique that hull shape more than the framing.
Most of his hull shapes come from the Sucher books or from the old Texas Dory plans, nothing special.
This one is a flat bottom, beach able dory style (Pacific Dory). They are beachable but they slam.
That hull shape has rocker, it will not plane easily and if it does, it will porpoise and have a bad trim.
The waterplane at the stern is too narrow for planing speeds. That shape is OK for a moderate speed boat, slow semi-displacement.
The shape of the bottom is very Skoota like. And you nailed it I'd say. Semi-d comes to mind.
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viewtopic.php?f=12&t=62495

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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by Christer »

OrangeQuest wrote: Fri Nov 16, 2018 8:17 am
jacquesmm wrote: Fri Nov 16, 2018 7:47 am Please don't build a Spira. Many of his boats are made with 2x4's, panels don't bend, difficult to build.
The plans Fallguy posted said over 300 feet of 2X4s and I counted 38 sheets of plywood of different thicknesses. To many different size screws to count. But I read on one of the forums that for one of his smaller boat the "fastener" kit was somewhere around $2500. That is a lot of screws! But I bet the boats show up good on radar! :)
The BearCat has a "Fastener kit" for the cuddy version - it alone is more than $1700. There's a lot of epoxy and fibreglass to be had for $1700.
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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by Christer »

cracked_ribs wrote: Fri Nov 16, 2018 3:41 pm Eastward is doing a cat about that size, I think they were coming in between 100 and 130 rigged.

Building a boat to fit that space is a six figure hobby. It's not for everyone. A boat that maximizes your slip that you can't afford to launch is less fun than a boat you can use.
That is a very good point, and one that's becoming more and more clear the more I look at various designs. The size boat I want is exactly opposing the idea of an economically driven hull, unless I go for a Skoota 24 or the Jazz 30. Those designs are economical to run, but the beam is a problem.

Even after bothering so many people, it seems likely that I'll never get to build anything.
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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by BarraMan »

Christer, this has to be the most exasperating thread I have seen. You have talked about building boats from 21’ to 30+’ on the one hand, while on the other hand you talk about “economy” and saving on engine costs.

I don’t know your personal circumstances, but there are HUGE differences between the build, fit-out and operating costs of a 20’ vs a 30’ planing boat!

Given that you are looking at 25 - 30’ outboard powered boats, and the cost of petrol/fuel in Europe, I assume you have deep pockets! :doh:

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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by fallguy1000 »

BarraMan wrote: Fri Nov 16, 2018 5:10 pm Christer, this has to be the most exasperating thread I have seen. You have talked about building boats from 21’ to 30+’ on the one hand, while on the other hand you talk about “economy” and saving on engine costs.

I don’t know your personal circumstances, but there are HUGE differences between the build, fit-out and operating costs of a 20’ vs a 30’ planing boat!

Given that you are looking at 25 - 30’ outboard powered boats, and the cost of petrol/fuel in Europe, I assume you have deep pockets! :doh:
Pinning down the SOR better is important.

Reconciling speed vs fuel economy is one.

Max length and beam another.
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Re: Christer's planning-to-build-a boat-at-some-point thread

Post by cracked_ribs »

Christer wrote: Fri Nov 16, 2018 5:05 pm
Even after bothering so many people, it seems likely that I'll never get to build anything.
Well, why not start with that boat for your daughter, and scratch the itch without having to make all these decisions?

I had planned a large build myself, but then the company I do most of my work for changed their minds about where they needed me, and instead of going back to a space I could build in, I had to stay in the middle of a city where a house with a yard is two million dollars and a garage is another million, so I'm in an apartment.

I couldn't start the build I had planned, so I built a new dinghy because I could fit it in my apartment.

I have a book that is nearing completion, but it's hard to get paid real money to write a whole book. But I wanted to keep writing, so I wrote articles in my field of expertise and I have tens or hundreds of thousands of words in print because I worked small when I couldn't work big and it added up.

If you want to build, you build. You don't start with your magnum opus. You just start.

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