A Houseboat that Sails?

[NolensVolens]

This bottom-coppering technique has been used by Dave Zeiger of Triloboats, and I intend to follow his lead on this. My one concern is that according to some reports in tropical conditions copper does accumulate hard growth. The copper to use is medium-hard roofing copper.

 

[goodwilltoall]

Think predrilled holes would be difficult to work with and almost inevitable some misalignment causing a percentage of hull punctures.

What about slightly elevated bolts or screw in lags with copper sheets set on them and then slighly tapped identifying areas for drilling. A heavy tar bed can then be applied prior to installation.

 

[NolensVolens]

The holes in both the copper and the plywood are going to be drilled using an NC mill (a ShopBot, most likely). The positional accuracy is +/- 0.005in (0.127mm). Misalignment would happen only if there is a programming error.

 

[Angélique]

- Vaguely remember a 130 avs number which is comparatively good so would think the completely flat deck would really destroy that value. That is if its really a factor you are concerned about.

Not sure what you mean by avs. The hull has 130º primary stability and isn't particularly stable when floating upside-down. Is that the number you are referring to?

AVS = Angle of Vanishing Stability​

 

[NolensVolens]

Yes, AVS = 130.

https://2.bp.blogspot.com/-UvO4aUqz...4IdP6-byK46-fcpgCLcB/s400/Righting+Moment.png

 

[goodwilltoall]

Impressive the NC cutting machines.

Completely flat deck reduces rerighting, acting as suction cup upon the water as racing boats have shown. So 130 maybe an inaccurate number.

 

[NolensVolens]

Impressive the NC cutting machines.

Completely flat deck reduces rerighting, acting as suction cup upon the water as racing boats have shown. So 130 maybe an inaccurate number.

I have no idea whether Orca3D software figures in the "suction cup" effect; I'll have to take it up with them. But I do know that a non-flat deck would be a nonstarer when it came to being able to tango passionately all around the deck, and that's a must-have requirement according to #1 client.

There are deck arches, two of them enclosing somewhere around 16 cu. ft of air. In a knockdown they are designed to provide additional buoyancy above deck. They more than make up for the lack of a cabintop or an arched deck. They also house the sheet travelers, serve as air intakes for ventilation, provide supports for a canvas awning or a winter tent, house electronics, provide mounting places for nav lights and deck lights, have hooks for hanging hammocks, and a high place to stand to work on the rigging or to gaze at the horizon. I don't know how life could even be possible without deck arches.

 

[Angélique]

Watertight deck lockers when mounted at the bulwarks add buoyancy too where it counts to resist to roll further in a knockdown, and so they're increasing the boat's AVS value. When mounted at the deck centerline the added buoyancy will foremost decrease the boat's initial upside-down stability by getting the boat's center of upside-down buoyancy down.

 

[Angélique]

Completely flat deck reduces rerighting, acting as suction cup upon the water as racing boats have shown.

1. There's no such thing as "suction cup" effect in violent waves I believe.
   
   
2. Quidnon's high free board will put her ballast high aloft when upside-down. This upside-down high center of gravity decreases her upside-down stability. Then wind and waves hitting the high free board and the rocking of the boat on the waves will knock her back on her feet I think. This isn't in the calculations as wind and waves are not always there, but most likely there's a lot of it when going and being upside-down.
   
   
3. Bad luck for Racers since they lack this high free board feature, and they have a taller rig which damps rolling back more, and they have often more sail aloft as a cruiser when going upside-down which also damps the rolling back more, hence they're more likely to stay upside-down.

Dutch link:

 

[Angélique]

So 130 maybe an inaccurate number.

1. 130° = AVS = the equilibrium before going upside-down or back to right-side-up, but when upside-down she also has to pass the same equilibrium to get back on her feet, so her upside-down AVS = 50°.
   
   
2. If she had a trunk cabin then the missing internal volume of the lower positioned aisles ^a/ gangways ^b would take away a lot of buoyancy where it counts most to resist to roll further in a knockdown. So then her right-side-up AVS would be much lower and her upside-down AVS would be much higher. Her initial upside-down stability would be smaller though, as the center of her upside-down buoyancy would be lower placed with a trunk cabin.

^{a & b} I'm not sure what's the right word in the above context: ^a aisle = US English ? - or - ^b gangway = UK English ? - Is there a common English word for it ?

( In Dutch it's ‘‘gangboord’’ )​

​

P.S. - I've never understood walking down the aisle . . .

 

[yves]

The rudder blades seem a bit big to me, and why having the mechanism so outside the boat ?
In any case cool looking project !

 

[Angélique]

Re post #12 and #15:

The prop has to have the right pitch, and then everything works nicely. . . . . . . . . .

That's is only for ¹/₇ right as it only mentions 1 out of the 7 points you need to take care of to make everything work nicely for a particular boat:

1. - The chosen engine needs to produce the right amount of power.
2. - The chosen engine needs to produce the right amount of torque.
3. - The chosen transmision needs to have the right gear ratio for the choosen boat + engine + prop combination.*
4. - The chosen prop needs to have the right diameter.
5. - The chosen prop needs to have the right pitch.
6. - The chosen prop needs to have the right number of blades.
7. - The chosen prop needs to have the correct rotation direction in relation to the engine.
8. - Nothing is right if it ain't all together right. - So each point has to be right in relation to all other points.​

* For this boat (in post #1) a High Thrust outboard version would be the best choice I think.

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A High Thrust outboard version vs. a Standard outboard version has:

- In general¹ exact the same engine with exact the same specs, so the engine has exact the same power and torque output at exactly the same revs at the crankshaft.
- A higher gear ratio, this means lower revs and a higher torque available at the prop shaft.²
- Often the ability to house a larger prop diameter.³
- Often a more durable transmission.⁴
- Often a more durable leg.⁴
- Often a bit more weight.⁵
- With the right prop more thrust at low boat speeds⁶ compared to the Standard outboard version with also the right prop.

¹ Meaning: for most brands with High Thrust versions of outboards in their program.

² More torque delivery at the prop shaft means a higher force load on all components in the transmission and leg, especially on the bevel gears in the end.
- Therefore manufacturers often choose to use the next size up leg for High Thrust versions.

³ If the manufacturer has chosen to use the next size up leg for the High Thrust version then there's room for the next size up prop diameter.
- If the manufacturer choose to use the standard leg with only a different gearing for the High Thrust version then there's only room for the standard prop diameter, and then often a 4 blade prop instead of 3 blade is used for the High Thrust version, as often just more pitch on the small diameter 3 blade prop would be less effective for this application.

⁴ If the manufacturer has chosen to use the next size up leg for the High Thrust version then the force on all components in the transmission and leg will be lower than on its original design application. Hence less wear and thus more durability.
- If the manufacturer choose to use the standard leg with only a different gearing for the High Thrust version then the force on all components in the transmission and leg will be higher than on its original design application. Hence more wear and thus less durability. Plus the higher force increases the chance that some components will break even before they're worn.

⁵ If the manufacturer has chosen to use the next size up leg for the High Thrust version then this will add some weight.
- If the manufacturer choose to use the standard leg with only a different gearing for the High Thrust version then the weight will be almost the same as with the Standard outboard version.

⁶ With a low speed of the boat the prop grips better on the water when it has a low speed itself. To realize this the prop needs to produce more water displacement per rev. And to do so the prop needs lower revs and a higher torque at the prop shaft.<sup>7

7</sup> Note: the power at the prop shaft remains the same as with the Standard outboard version. This is only about the High Thrust version's more effective way to transfer the power to the water at low boat speeds.

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How to know if a High Thrust outboard has the next size up leg or the standard leg with only a different gearing:

First indication from the specs is weight:
- If the High Thrust version has more weight than the Standard version then this is an indication for the next size up leg.
- If the High Thrust version has almost the same weight as the Standard version then this is an indication for a standard size leg with only a different gearing.

Indication from the ability to house a larger prop diameter:
- If the High Thrust version has the ability to house a larger prop diameter than the Standard version then this is an indication for the next size up leg.
- If the High Thrust version only is able to house the same prop diameter as the Standard version then this is an indication for a standard size leg with only a different gearing.

Indication from the availability of props with a larger prop diameter as for the Standard version:
- If there are for the High Thrust version props available with a larger diameter than what fits in the Standard outboard version then this is an indication for the next size up leg.
- If there are for the High Thrust version only props available with the same diameter as for the Standard outboard version then this is an indication for a standard size leg with only a different gearing.

Visual indication from pictures and/or videos and/or seeing it IRL in the flesh:
- If the High Thrust outboard's leg looks and measures a little beefed up compared to the Standard version's leg, and/or there are other differences, then these are indications for the next size up leg.
- If the High Thrust outboard's leg looks and measures exactly the same as the Standard version's leg then this is an indication for a standard size leg with only a different gearing.

And just ask:
- Ask the dealer and/or the importer and/or the manufacturer etc. etc.. - And seek confirmation for the info they give . .

Good luck !

Just saw in a Suzuki brochure ^PDF a sketch that quite nicely illustrates a High Thrust's beefed up lower leg unit . . .

(bottom part, of page 3, of the above linked brochure)​

Suzuki outboard leg, lower unit, principle illustration, DF50AV(50Hp) + DF60AV (60Hp) high thrust series.

Note the pink sketch of the high thrust lower unit around the lower unit of the standard Suzuki 50 and 60 Hp outboard versions. ↑

P.S.

Below from the thread: Repower Inboard Prop Pocket Hull with Outboards ? → post #11, a more standard list of matters to take note of when selecting an outboard...

There are at least 10 points you need to take care of to make your outboard work nicely on a particular boat:

- 1. - The chosen engine needs to produce the right amount of power.
- 2. - The chosen engine needs to produce the right amount of torque.
- 3. - The chosen transmision needs to have the right gear ratio* for the boat + engine + prop combination.

* High Thrust vs. Standard outboard version.​

- 4. - The chosen prop needs to have the right diameter.
- 5. - The chosen prop needs to have the right pitch.
- 6. - The chosen prop needs to have the right number of blades.
- 7. - The chosen prop needs to have the correct rotation direction in relation to the engine.
- 8. - For outboard motor pairs choose a standard rotation version, and a counter rotation version, to eliminate prop walk.
- 9. - Choose the right leg length in relation to the transom height to the water.
10. - Nothing is right if it ain't all together right. - So each point has to be right in relation to all other points.​

 

[Silvertooth]

Large outboards are problematic and have short lives in my opinion.

I would prefer smaller outboards that are cheap and more reliable.

You could have a spare outboard motor on board and easy enough to change it in a hurry.

Or a perfect combo these days isn’t an little electric outboard and a petrol one, the petrol one could charge the battery then use electric one of about the same size, or on rare occasions you could use both together if needed.

 

[member 76956]

Hello to all

I've been thinking along these lines for some time and just wanted to introduce myself.

I've been a sailing enthusiast for some time and want to hook-up with those who are or who have been on the same journey.

I'm still looking at hull shapes and am grateful for your work. In that vein, I've been looking at barges and pontoon boats as base platforms. I've also been considering the idea of a seagoing flatbed-truck, that can be reconfigured for multiple purposes, such as a houseboat, with the houseboat shallow-draft and beachable and the load; houseboat, in this example, being demountable.

Other types of loads might include cargo-containers, manufacturing and studio spaces, restaurant and retail, again all demountable.

Hope you find some of my ideas interesting and I get to hear from some of you.

Cheers.

 

[John Rivers]

It seems far cheaper to just convert some old Hatteras or something with a droppable keel and a small sail.

I've been wanting to do this same project but it's just too expensive and I have opted for tent structures on top of a boat as sleeping area, and just add some quick setup insulation inside the tent and a kevlar mat for the stove. Makes alot more room for below the deck.