Aluminium boat Panama

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kens
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Re: Aluminium boat Panama

Post by kens » Thu Apr 26, 2018 2:00 pm

Double Eagle in aluminum
You can delete or change the cabin as required.
The running bottom of Double Eagle is what makes it go.
runs well in heavy seas and still gets up on plane.
I stretched mine to 24'8" and I love it.

my avatar is it on first launch.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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Bill Edmundson
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Re: Aluminium boat Panama

Post by Bill Edmundson » Thu Apr 26, 2018 2:15 pm

We've seen the Double Eagle stretched to over 30 feet. Ken, I think the DE would be a very good option! I'm not sure about 16 or 17 people in any of this size range boats though. I can't tell you that. I don't know what the USCG would say. But, this is not the United States.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

niko
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Re: Aluminium boat Panama

Post by niko » Thu Apr 26, 2018 5:32 pm

Ok so I understand that i can use 6061 for wet parts but 6063 only if i have to and only on dry parts.
Is there an issue on having those boats in the water all around the year?

I havent looked on the DE before but it seems also a nice option. what are the pros and cons compared to the la paz?
By the way there are no boating regulations in any form.

A dedicated ac welder in this range is outside my budget. I know it would be quite helpful but we might have to start with the rough transformer solution of my airpak. therefore we are planning to use as much mig as possible because i think the mig setup should be pretty ok.

I will definitly have a read on yours and other post and will also make a building thread as soon we start.

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kens
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Re: Aluminium boat Panama

Post by kens » Thu Apr 26, 2018 5:56 pm

LaPaz:
deep vee
shorter waterline length
wider beam
hull depth shallower

DoubleEagle:
deep vee bow entry, nearly flat transom
longer on the waterline
6" less beam
4" deeper hull

Everybody wants a boat that carries a load, runs fast, uses little horsepower, and fuel economical, runs in offshore waters, right?
Well, you can't do that. You gotta pick your wants and needs.
A flat bottom carries the best load, deep vee not so well
A deep vee cuts thru big waves, a flat bottom will beat you up in bad water
It takes less horsepower to push length than beam
in bad weather, freeboard is your friend
Deep vee's do not run well at the 'speed you need' in bad seas.
Double Eagle runs well at the speed you need in bad seas.

My take on it?? Stretch a Double Eagle
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

Kevin Morin
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Re: Aluminium boat Panama

Post by Kevin Morin » Sat Apr 28, 2018 12:31 am

niko, kens, Bill,
the open ocean aspect of niko's boat is what makes the La Pas a bit more useful running an hour out in the Pacific. Since the DE is a warped bottom to a nearly flat transom- the hull can run over a swell or wave and end up with the running waterline well aft amidships. This won't happen in fresh water to speak of. The La Pas is warped too, as near as I can learn without a lines plan. But the 18deg stern indicates it carries more deadrise farther aft than the DE?

In the ocean the combination of speed and waves will leave most planing hulls to impact (re-enter the water) aft amidships and that is why niko experiences the impact with his existing panga- not just because of his flat planing and beaching surface. If you notice the inverted hull he posted? the deadrise either side of the beaching plate is not exactly steep! I'd say 10-12 degrees? Add in the missing V along the keel and the impact is jarring.

Further the running speed is not slow- so the hull pitches up and runs "off" a swell- and when the CG passes over the swell (running waterline's leading edge) the bow pitches downward into the trough. That is the point of impact that niko is looking to avoid (without expensive cushioned pedestal seats?) so his guests are not fatigued when they reach his island.

Therefore a deeper V hull, like La Pas, versus the DE will offer more deadrise, farther aft, for a softer entry at a farther point aft the bow- and that will translate to a softer ride in a head sea- at speed.

Also, the DE is a skeg/inboard/keel boat design? Isn't it? That will not beach well- the keel will exaggerate the heel over on one chine and keel boats will actually swamp when the tide comes back in- unless they're propped with poles or some other means to remain upright. An outboard powered DE may beach better than a La Pas but- the critical path I understand is the quality of ride for the hour out to the island? I'll expect the deeper V gives the better ride.

I'd recommend the La Pas over the Double Eagle due to the long -one hour- run off shore in a Pacific swell. The deeper V will take more power to give the same performance/speed/agility but.... the reduced jarring as it runs seems to be desirable in niko's application?

I may be weighing niko's remarks inappropriately?

Cheers,
Kevin Morin
Kenai, AK
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kens
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Re: Aluminium boat Panama

Post by kens » Sat Apr 28, 2018 5:51 am

The DE is not just a inboard. The plans include outboard, IO, and inboard power details, and different skeg alternatives.
I built mine with no skeg at all.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

Kevin Morin
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Re: Aluminium boat Panama

Post by Kevin Morin » Sat Apr 28, 2018 10:45 am

Kens, I've only viewed one DE build in metal (various metal boat sites online) and that had a traditional inboard keel and rudder so wasn't aware of the other configurations. Thought the design was for an inboard only?

The flatter after sections of the DE will sit on the beach better than the La Pas for sure, but running in a head sea seems niko's main reason to move to another hull? The V will surely make the run less jarring (IMO) in a seaway.

cheers,
Kevin Morin
Kenai, AK
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niko
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Re: Aluminium boat Panama

Post by niko » Sat Apr 28, 2018 11:38 am

Actually yes. The focus is on smooth ride in rough wind chop. But I am considering doing la paz first and making a DE second. We always need mire than one boat and it would be nice to compare them.

Oh and we work the carribean which is quite different to panamanian pacific because of winds and wave periods.

And about the speed; we only go full throttle on flats behind the reefs or ind windless times so top speed is not our focus

Kevin Morin
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Re: Aluminium boat Panama

Post by Kevin Morin » Sat Apr 28, 2018 1:01 pm

niko, you're a tad slow in giving us a picture of the real conditions!!

If you're not interested in high speed in a seaway- then the DE hull will carry more wt for a given seaway onto the beach than the La Pas, note: a deep V will give softer or less impact in the same seas by the bow- compared to the DE but.... given the after sections being shallow and flatter than a La Pas- the DE will carry more wt (people) onto the beach farther up the surf /water line than the deeper V hull.

Using an outboard engine (or a pair) and keeping a close eye on the throttle, the flatter after sections of the DE will give good service- just slow down when you pound- and... the hull shape will beach much farther up the beach grade than the La Pas. The inclination of the beach- grade or slope- relative to the water will determine how many boat lengths farther up the beach one hull will land vs the other (given the same loads) but the flatter hull will definitely beach farther up.

Sorry to mis-understand that you were on the Pacific side of the country! Even so, if you're going to run hard into a head sea the sharper bottom will give less impact- but if you and your helmsman pay any kind of attention to the sea state- you'd be fine in a DE - but you'll have to slow down more often when there's a breeze and swells by the bow.

I've done a couple of hulls similar to the DE's lines - they do ride a bit hard at speed but they beach very well and the client in each case made that a higher priority than the highest speed running into the seas. On the other hand, I've done a few small boats where the V was much higher deadrise and they were able to maintain higher speeds running into bow-on waves by comparison. These latter boats are 'never' put on the beach, they run from dock to dock or trailer to docks- but don't land as part of their owners' normal use.

cheers,
Kevin Morin
Kenai, AK
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kens
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Re: Aluminium boat Panama

Post by kens » Sat Apr 28, 2018 4:19 pm

It has been my experience that few people run wide open in when the seas are an honest 4-6footers with the occasional 8footer.
I wish I had more power (speed) in flat protected waters, but then, that is not the most miles I put on it.
What speed do you really actually run in those head seas? You running 30 knots? If so, how do you keep your fillings in your teeth, no matter the type of hull?
My DE has been out in Small Craft warning seas. The boat can take more than I can. I have seen the hull supported by the bow & stern and apparently the center was lifted out of water, the waves were that close and that steep. I been surfing down the back side of following sea. I been on top of a following sea wave, and maintain staying there, and clock 15mph on GPS. Then turn around and make 15mph into the seas, and wonder why your getting beat up at a mere 15mph. Because your making 15 then the seas are moving at 15, so the closing speed into the weather is in effect 30mph.
So, I slow down to 12mph such that I am only encountering the seas at 27mph.
If you look at the lines drawings of both hulls, the DE, up forward in the bow (where the seas meet the hull) may be a little deeper Vee.
I have come off a tall following sea wave and stuff the bow into the next one, and split green water above the gunnels up front.
These things I dont like, but I have seen this.
Also, after seeing these things, and knowing I do not have a skeg at all, I would not want a full size skeg. I would like a small skeg, but not much.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

niko
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Re: Aluminium boat Panama

Post by niko » Sun Apr 29, 2018 8:12 pm

Ok I will keep on trying to explain :wink:
We transport people all around the year and in the high season which is january to april its also windy season which means between 3 and 6 bft everyday bit we still have to keep working or even more so.
So I really want to try using a deep v first because there are none in the area to try out and it could be really a game changer for tourists commodity.
The spped is secondary and we always adapt speed to circumstance which often means half or even less throttle. So being able cutting travel time would be an interesting feature on bad days.

So landing could get a bit more difficult, but I would trade that in for better travel experience. Also I have a few ideas to make landing easier.

Kevin Morin
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Re: Aluminium boat Panama

Post by Kevin Morin » Mon Apr 30, 2018 11:30 am

niko,
these remarks are about beach landings in small welded boats. Perhaps not applicable to your island's beaches but worth mentioning so you can explore if they're useful or if some element of these methods might be adapted to your own landings?

First is adding UHMW plastic strips to the outside of the hull- depending on design (transverse) sections- I've put these strips on a 'shoe' or box keel added to the hull to hold the strips and to various 'rails' or extrusions added to the boat's outer hull that held the fasteners for the strips. Both have advantages and disadvantages depending on hull shape and beach material.

We have many gravel or semi-gravel-not-really-sand beaches and the commercial fishermen land on them regularly using the plastic strips as one method. These strips provide enough reduced friction to allow the boat to slide up the beach a few lengths before stopping. So the operator heads for shore- on plane- and lands by kicking up the outboard engine's leg/prop and sliding the boat until it stops.

Again, shape is critical to this method of landing on plastic strips - where your panga hull would use this method easier than a V.

Next is the "corduroy" of buried logs in the beach. These logs are buried parallel to the water's edge/surf line about 2' (maybe 3') apart leading from the water at low tide to the waterline at high tide and above. We have a nearly 30' tide reach so they're quite a construction project here.

Also finding a nice steep beach in our area can be a challenge- so in your area that may actually preclude this method's usefulness? If the tide is small in range (under 5' high to lo) and the beaches slope very gradually- you'd need a lot of logs! to get the boat 30' or 40' up the beach.

However, the method of landing 'dry' is to run at the logs, buried so that only an 1" shows above the beach surface, and slide up the logs until the boat stops. Takes a little practice - and it's an exciting event if you're riding the boat and don't realize what is about to take place! On the other hand, this beach landing method does work well with welded metal boats as they are nearly impervious to this low impact and aluminum generally slides pretty well on even dry beach logs.

Just a couple of ideas that are in use to improve landing through the surf onto a beach with loads in small welded boats. The commercial fisherman's goal is to get the boat above the surf line by one boat length in order to put a trailer over the boat or to get the fish out without having to fight the swells moving the boat if it remains in the swells or surf.

https://www.youtube.com/watch?v=cId_jbiSuqY net skiff landing one length, no corduroy or plastic strips
https://www.youtube.com/watch?v=mXRPYVEDPvE here's a portable corduroy put down by friends- but you could bury them and always land in the same place?

Cheers,
Kevin Morin
Kenai, AK
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niko
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Re: Aluminium boat Panama

Post by niko » Thu May 10, 2018 7:42 pm

These thoughts and examples on beaching are very interesting. Our beaching id quite easy compared to what you are describing. We just get our stem a few feet up the sandy beach to unload people and stuff and retire to anchor in deeper water. Our tides are max 3ft on the carribbean so not a real factor and we hardly put the big boats up the beach.
But i am thinking about installing a downside hinged door on the frontside maybe with a floating extension to make it more comfortable to exit the boat. Just an idea

Now my plans have arrived and we are starting to mentalize the project.
I am also halfway through the book and through kevins great posts on this forum.
The full patterns are great but I still need to figure a few things out.
It looks like the transverse frames are floating on the longitudinals cause the lower transom outline is 4in lower than the 1st frame underside. Do I get this idea right? What are advantages and disadvantages of that design compared to plate touchin frames?

I am highly considering the delta pad but I would like to understand how that could be executed on this.
Which of the two drawings maje sense? Itsthe transom view. The 1st could be retrofittet I suppose? Its the one the pqngas also use

Tomorrow I will get quotes on material availability and prices.

Thanks for all the help!
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Kevin Morin
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Re: Aluminium boat Panama

Post by Kevin Morin » Fri May 11, 2018 1:07 pm

niko, the idea of a bow 'door' or bow ramp (passerelle for those who like correct nautical terminology) is well within a metal boat design modification- but adding a gang plank/retracting ramp/bow door ramp.... or whatever we should call such and appendage is going to seriously modify any design that does not already have that feature designed into the hull's plans.
niko wrote:But i am thinking about installing a downside hinged door on the frontside maybe with a floating extension to make it more comfortable to exit the boat
So, while I'd say the idea was perfectly valid in the boat you're planning- the bow sure does need to change from standard construction to provide a clean job of the bow ramp execution!

If your lofting skills are high enough- you can create frames (transverse) that will touch both the hull and hold the longitudinals to the hull panels as well. Even with patterns - many builders won't have the needed skills to loft and correct any small imperfections in the overall shaping of the hull's frame elements to make a hull/skin/plate to frame fit uniformly. So, holding the frames back a few mm from the hull allows the metal boat builder to fair the hull using the longs- exclusively in contact with the hull plating/sheeting.

This method may be drawn into your plans and patterns? The plus side of this type of fairing and framing is that the frames can be built more rapidly- with less concern for the small fractions of an inch of layout, fit, shape, welding and re-fairing. In this method the frame notches that hold the longs can be left a bit 'shallow' so they can be filed/sanded/cut deeper as high spots are discovered during the fairing process- further this level of control of plating by using the longs simplifies the process of detailing both the x-verse frames and the longs together.

The strength of welded boats is often difficult for the wood or glass builder to fully grasp and appreciate - not all parts have to touch and be welded together to achieve a sound and single piece hull. The longs can 'float' in the frames and weld with stitches to the hull plate as long as they're still welded into the notches of the transverse frames; the result is a single piece hull.

on the other hand- if you start with the table off offsets, and lofted the hull yourself- full size- instead of relying on patterns you can cut, form, weld and fair transverse frames that will touch the hull and hold the longs BOTH in a fair planked or sheeted hull. It is a matter of choice and skill/familiarity/method preference which idea you select for your build.

A builder who buy patterns; can then fair the frames they build- then notch for longs (or adjust existing notches) and end up with both elements welded to a fair hull.

Main issue with frames touching the plating is the transverse welds can distort the hull much more readily than longwise welds.

The delta pad on a V bottom does not run through all the V sections as sketched. Instead it would begin a 0 width - about 1/2 the hull and ramp up and widen as it ran aft.

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin

niko
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Re: Aluminium boat Panama

Post by niko » Fri May 11, 2018 4:46 pm

I am without the patterns for the weekend but maybe I didnt perfectly get them. Will have to study them again. Everything is first time so it will take me awhile or even a boat to learn the most important steps.
I thought the transom on the full size patterns wss drawn at exact position related to the frames but this could be a mistake. Have to look again.
Do the glenl plans include information to for lofting? For practicing it could be interesting.

Today I got all information about material.
I can get 1/4, 3/16 and 1/8 in 5052 and flatbar, angles, channels in 6061
3/8 plate to cut the stem only 3003

My questions:
What should I use for the stem? 3/8 flat bar in peaces to make it fit? 1/4 plate and cut it out or 3/8 3003?

For the longs should I use 1/4 6061 flat bar or should I cut strps of 1/4 5052 plate?

Shoukd the delta pad end at the transom like in picture 1 or 2?

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