Starting Rescue Minor in Plywood HELP

[river guy]

I have choose the Rescue Minor because of our moving sand bars and river weed (mill foil). My boat building experance is little my woodworking experance is good. My shop is OK but will improve as tools are needed. I spent my life figuring out how to do things for other people now it is my turn. The one comment I don't want to hear is don't do it.
I do not plan to follow the plans to the T. Don't think I could bend that 3/4 inch ply.
What I am thinking.
change the rabbited chine to beviled and butt the plywood then cover with glass. what dimensionsfor the chine?
Change the keel (flat bottom) to 3/4 inch Okoume in place of the 1 inch 1942 plywood. maybe run a couple of stringers.
The bottom laminate two layers of 1/4 Okoume plywood.
The sides 3/8 Okoume.
Deck 1/4 Okoume.
I came from the aerospace world so can not help to think light.
I am open and would like to and need your comments.
Thank you

[Tom Robb]

Light is nice, but most boats seldom need to take to the air.
Robb-White's son is around. You might discuss your ideas with him.

[Paul Pless]

That design has been a popular topic here of late.

A quick and dirty search reveals these threads: Search for Rescue Minor (http://www.woodenboatvb.com/www/vbulletin/upload/search.php?searchid=56883)

[river guy]

Yes thanks I have been following it for a few weeks.

[Thorne]

Sounds like you are building to the original Atkins plans, not trying to copy the highly-modified version that Robb White built, right?

http://www.boat-links.com/Atkinco/Utilities/images/RescueMinor-2.gif

Been checking out the yahoo group? Subscribe: AtkinBoats-subscribe@yahoogroups.com

My suggestion would be to follow the plans closely -- but if you want to change things, pay most attention to the dimensions and shapes. I understand that the tunnel shape and prop size and placement are **critical** for the propulsion to work.

Don't go too light on the bottom if your waters may include hitting bottom occasionally, trailering on rough roads, or sitting out low tides on uneven ground.

Will you use an old shaft motor as per plans, or try some sort of mod with an outboard? All very tricky stuff as I've heard, mostly as above with prop size and angle in the tunnel, but also sealing the tunnel as it sort of pulls up the water into the prop.

Good luck and have fun building!

[river guy]

For a engine I am considering the Yanmar 22HP diesel. With gears it is a little slow in revs I am looking at a 10 dia 12 pitch prop. (which comes first the pitch or dia) I tend to agree about the bottom thickness. Yes I plan on keeping the shapes as designed. Hope to make it look like the original.

[Wes White]

I think 3/4" on the flat bottom would be fine, especially if it is fiberglassed. That is the only part that hits if you run aground. Laminating the rest out of two layers will be aggravating, but will make it much easier to get the shape right. My father was extra careful to duplicate the tunnel exactly as Atkin had designed it. That was the only lofting I ever saw him do. I am running a 10 1/2 x 12 on it now (I have always put the diameter first). 22hp should be fine, but I don't know about the gearing. He rigged his belt drive to give the same rpm at the prop that the plans specified. Lightweight is good, but he did find that his will cavitate running light. A bucket of water or a big cast-net on the bow fixes it. He was sure that, built to Atkins planned weight, it would not have been necessary. Sorry for the long post.

[river guy]

Thanks Wes, I need long posts I have a lot to learn. I keep you posted on the engine and gearing. I am looking forward to making this.

[StevenBauer]

Wes, you've been a member here for over five years. And you are an experienced, inovative designer/builder of cool boats. No need to apologize for long posts. I for one would welcome hearing more from you. The longer the post the better. :D

Steven

[Spokaloo]

river guy: Hey imagine the irony. I live on Long lake in Spokane! I just received my plans from Pat this week and am going to be tackling her over the winter as well. I had planned to go the 1" on the flat bottom and 1/2" or 3/8" okume on the tunnel. 3/8" or 1/4" on the vertical surfaces, and a lovely layer of 8oz to protect her.

PM me if you get a chance, this could be a fruitful coincidence as we could build simultaneously.

E

[Tylerdurden]

Mine is going together cold molded, I found it the only practical solution to my abilities. I am making molds so I can build another because I have some weird ideas I would like to try.
Following Robbs build and with his encouragement I am considering running a kitchen rudder on number two. The drawings are comming along and there is a bit of machine work involved. It seems like a perfect combo but I am nuts anyway so if I muck it up or have to start modifiying it I find it better to have one good example left.
RW's setup was incredible and I thought I would give it a go, but the whole point I think he was trying to make was to go "your own route" so here go's the batty Kitchen rudder idea.

Back to cold molding I felt layups of 3 or 4 mm would do the turns well and allow me to get that full one inch on the bottom.

[river guy]

I like to hear more of your cold molding The design botton is 3/4 inch with a 1 inch flat keel how are you working the layers into the deadwood in two molds like Robb White strips?

[Tylerdurden]

I am building molds to support the frames on a strongback. steam bending the oak and laminating the keelbox and knees. I will layup on that then flip her. I think that is probally the simplest method. I will still end up with a 1" keel and 3/4" sides, just stonger with the diagonals in the layed up sheets. I am trying not to deviate to far from the original plan. I hope to be starting this month but I had to have some site work done to set the bow roof shed on. The site is almost ready
with all the excavation done. Three feet of topsoil and a lot of stumps later, Drainage ditch in. Just waiting a couple of days for it all to dry out (3" rain in 6 hours this weekend) then the base goes in.
The shed is 32x14 and woodstove equipped with an out building next to it for storage and the like.
I will pop along some photos as it goes together.
I envy the guys that have readymade shop space. Its as big a project to get ready as building the boat itself.

[windmill4048]

I see you're considering a Yanmar for power. Yanmar certainly has the rep for being a very sound marine engine.

I looked at Yanmar, Universal and Beta. Both Universal and Beta use the Kubota tractor engine that Robb White used as their core. They then add the stuff you need to make a marine engine.

I found Yarmar the heavest and most costly and Beta the lightest and cheapest. Beta seems to have done a good job pull all the stuff you need to reach/check out of dark corners and putting in invery accessable places. Beta also provides a short parts list cross referenced to "tractor" parts so you can buy spares at farm store prices rather than boat shop prices.

[river guy]

I have not made a engine selection and the and I like the farm parts bit I live in farm country to bad John Deere dropped its small diesel marine engine. I am a diesel fan and will probably run BioDiesel. But I also want quiet. I do want to have a engine that is ready to install in a boat either by conversion of manufacture. The controls must be easy to use as it will be operated by everybody from above my lead Husky she only gets to steer.
Engines are a problem The RPM have increased since 1942 even the new diesels are running faster than the gas of that time. The Rescue Minor plans call for a 10X12 prop. And a shaft speed of 2000 RPM. Most of the new diesel max out at around 3700 RPM with the torque starting to fall of around 2600RPM. The transmissions I have found are have a 2 to 1 reduction or greater. To achieve the RPM recommended for the RM this would call for a 1.35:1 reduction to stay above the torque curve. I see why Rob White was using a belt drive I believe he was running his engine at 2700 and the prop at 2000 RPM with a 10.5X12 prop. I don’t understand his reverse.
My questions are:
Is there another engine
A transmission
Am I missing something?
What about increasing the pitch of the prop. We are stuck with the 10 or 10.5 prop inch dia.
What about a three blade etc.

[Spokaloo]

Guy, a good agriculture option is to go into the local shop that carries combine parts. Combines have one powerplant that runs ALL equipment installed by belts ( except the hydrostatic tranny). Give them the rpm your engine makes and what you need your shaft speed to be. They should be able to come up with a V-belt system that will be smooth to operate, easy to maintain, and in the event you do foul the prop it will slip until you can get the powerplant shut down.

E

[windmill4048]

Most of the small engines I mentioned will be offered with a choice of gear ratios.

The Beta that I've looked at most carefully offers ratios of 1.45:1, 2.0:1 and 2.6 to 1 with the standard box.

Don't forget you'll want to cruse at an engine speed of 2,200 - 2,400 for best fuel consumption and peak torque.

By the way, I like the thought of exploring the combine drive system idea. I might look into that.

[windmill4048]

I agree that light weight is a very desirable goal. It makes the boat easier to "push", uses less fuel, requires less HP. easier to pull on a trailer.... Oh, and a light boat requires less material to build.

One of the really outstanding things about Robb White's boat is the amazing overall weight.

One thing Robb White did to reduce weight was to delete the fore and side decks and the coaming. He used an elegant and strong rail type gunnel in their place.

Not sure whether it's a good idea to eliminate the fore deck since it may add some strength and stiffness in the standard Atkin design. Maybe some of the experts here could comment.

By today's standards the boat is certainly over designed. We have a lot better understanding of how to use plywood today. And don't forget that this boat was drawn in 1942 and proposed for military coastal rescue service. That design point probably contributes to some extra weight from over designing for hard service.

Someone who knows what they are doing could probably take quite a bit of weight out of the plans.

[rvinson@cfl.rr.com]

The RM is a very attractive for fishing the flats in my area.RM has character, ecomony and the diesel is simplicity in running, if not in setting up.
Questions. Does anyone want to sell a Rescue Minor?
Would any that have built her want to share the cost to build the boat? Total project time?
Has anyone built her in 3/8 inch plywood plus fiberglass?
Are the plans of Mr. White's modified RM available for analysis and use for building?Is there a smaller version made for a fishing platform?
I'm confused with the machinery set up. The belt drive seems the way to go but has anyone perfected the forward, neutral, reverse shifting?
Finally, has anyone considered using an electric motor to run her? Too heavy with batteries? Too expensive? Too limited cruising range?

Comments:It seems to me that the design was put together to work around heavily defended shorelines and to bounce off obstacles, be they man or nature made. The 1 inch, even 1/2 inch, plus fiberglass seems very excessive for running the river flats of sand around here. Because she runs in 6 inches , unless one became careless, one should never run aground. I love the way she looks and the small inboard. The way she runs too.
Forgive the lengthiness and the number of qwuestions. I'm new at this but would really like to have a simple flats boat with character and performance such as the RM delivers. However, I have a lot to learn about the trades and cost of owning one.

[mcdenny]

Mr rvinson,

I have a light weight, skinny 25' launch with a brushless Etec motor turning a 12x11 prop at 1600 rpm max using a 2:1 toothed belt reduction. Electric drive removes the need for a transmission. Controller provides reverse and neutral = off.

Electric drive has several advantages but penalties, too, like battery weight and limited range. In my application (8) 6 volt batteries weigh 530 lbs and provide about 6 mph for about 25 miles range. The electric related parts (inc'l batts) cost around $4000.

[Uncle Duke]

Out of curiosity, regarding the discussions here about drives - has anyone here thought about hydraulic drive?

[StevenBauer]

I saw a cool 9hp honda motor today down at Hamilton Marine. It's meant to run hydraulics for a lobster boat. Might be a cool way to power a small boat.

Steven

[Tylerdurden]

Been some limited discussion, I have a lot of hydraulic control experience but have not looked at drive issues. 22hp continuous duty doesn't seen hard but the expense would seem to out weigh the cost of a conventional tranny. I am open to suggestions /ideas though.

[Canoeyawl]

This should really be a new thread, but I think about it quite a bit…
There is a loss of efficiency associated with Hydraulic drives, but in some applications that may make up for the inconvenience of other systems. I am working on a prototype detachable outboard drive that uses a 4 or 5hp air-cooled Honda (cheap, reliable, quiet!) stationary engine mounted in a cockpit locker and a hydraulic motor to drive a propeller. My application does not want the drag of a permanent shaft/propeller and power assist is not used frequently enough to justify the required space/weight and systems of a conventional inboard. I just row instead.
Because this project is for a canoe stern the mounting of a conventional outboard is hateful and problematic (mounted to the port side it is frequently swamped by wakes of larger passing vessels and impossible to sail on the starboard tack without dunking the engine) I’m often thinking about it. Most of the components are in place and just a few details left to finish; unfortunately my day job doesn’t leave much time for prototype toys!

[StevenBauer]

The 9hp Honda I saw today was $1500. I think the smallest diesel available is $4-5,000.

Steven

[Tylerdurden]

I flipped the issue of small marine drives at a hydraulic forum. I will report back to what I find out.

[Tylerdurden]

The 9hp Honda I saw today was $1500. I think the smallest diesel available is $4-5,000.

Steven

I scooped my 22hp yanmar for $2495 on e-bay, Found the timing covers to swap in a seawater pump for a couple of hundred two days later. I was going to belt drive the seawater pump but for that short money its cheaper to go with stock parts. I am debating if I am going to wrap the exaust manifold with ss tubing for exhaust cooling or go crazy and fab up a water jacketed manifold. Been looking for a stock manifold to fit it but they are very expensive for not a whole lot, if you know what I mean.

[Uncle Duke]

Tylerdurden notes:

There is a loss of efficiency associated with Hydraulic drives...

I'm no expert about hydraulics, but my understanding is that most of the loss is in the traditional swash plate, and that there is/was some improved gizmo from Molitech which reduces that.
Canoeyawl - maybe your hydraulic folks know something about this also?

(... sorry for the thread drift....)

[Spokaloo]

Good news; I know exactly where a half finished, plywood RM is. Jig is built, faired, and ready for sheeting.

Bad news: He isnt answering his email.

E

[Sal's Dad]

Nobody has ever built Atkins' Rescue Minor. Robb White confused things quite a bit, by building an Atkins-style Tunnel-Stern Skiff of his own design, and naming it Rescue Minor. There have been rumors of RM's, but I have been asking, and for a few years asserting that there are none existing, and nobody has stepped forward to claim otherwise.

There are several now in progress. (mine included)

There has been some discussion of Atkins Tunnel-stern on this board (search the archives) and considerably more on the AtkinBoats Yahoo group.

Questions. Does anyone want to sell a Rescue Minor?
See above. When I finish mine, I plan to review costs, production methods, performance, and market conditions, to determine if it would make sense to build more. Right now, my best guess is in aluminum, workboat finish, Kubota Diesel, it would cost maybe $20,000. Yacht finish, or wood/epoxy, maybe double that?

Would any that have built her want to share the cost to build the boat? Total project time?
We'll see...

Has anyone built her in 3/8 inch plywood plus fiberglass?
Building the keel much lighter than the 1" design would require additional framing. And the shallow draft just begs to be run in skinny water - what's the point of the boat, if you don't plan to run in waters far too shallow for others? So don't skimp on the keel. The "chine" and tunnel needs a bit of serious thought, or engineering, or trial and error.... Gunwales could be pretty light.

Are the plans of Mr. White's modified RM available for analysis and use for building?
There are no plans.

Is there a smaller version made for a fishing platform?
No. Robb mused about such a thing, maybe 3/4 scale, with a 6 HP... Not clear how this VERY unorthodox design will scale up or down.

I'm confused with the machinery set up. The belt drive seems the way to go but has anyone perfected the forward, neutral, reverse shifting?
Seems the way to go, but it is very unorthodox. Don't expect any support from the traditional marine power people. Robb perfected it, for Robb.

Finally, has anyone considered using an electric motor to run her? Too heavy with batteries? Too expensive? Too limited cruising range?
Funny you should ask... Last week on the AtkinBoats group (or was it Duckworks - after a while it's hard to keep the different fora straight) there was a discussion of just this. I believe the tunnel stern is a BAD design for low speed/low power/electric. A design with a small tunnel might work, but you should have no problem finding shallow-draft boats that will be fine with low power.


As to hydraulics, my understanding is that it is better suited for high-torque, low-speed applications. I thought about it for RM, but rejected it. (If anybody has any firm ideas how it could work - to turn a 2400+ rpm shaft, let me know ASAP!)

[rvinson@cfl.rr.com]

Mr. Denny Wolfe,
Thank you for your answer concerning electric drive. I looked at Elco Electric and their motors only go to 8hp and the cost and weight are both pretty high.

I wonder if anyone else would be kind enough to reply to some of my questions and comments.

Kind Regards,
Bob in East Florida

[erster]

Here are my thoughts on the subject of Rescue Minor and in general on tunnel drives in general. I still think Robb did it just "because" in my opinion but did it with a fair amount of experience in messing with boats. A tunnel drive with any inboard was and still is used for a boat when its primary use is shallow draft being the main use with a small craft. The net amount that you gain by using a tunnel is so little for the occasional boat these days makes it just not worth the trouble in more than one case these days when building a small hull out of anything that resembles wood.

Incorporating into a build hydraulics or even slip drive gear boxes was fine in the commercial industry. But for a pleasure craft the builder needs to spend more time and in some cases money and hassle for what it actually nets out in your favor. Another huge issue is down the road for any resale of the hull. A tunnel drive system is completely different than the tucked stern which was also incorporated in work boats and inboard engines with a shaft drive. In my opinion this is still the better of two evils if you are looking to minimize your draft with an inboard power system.

If you have never built a tunnel boat, you can build in a nightmare for handling if the tunnel is improperly designed and built into your hull. This renders your boat a bastard in almost all cases when in use.

Nothing is above doing and much easier to do it wrong than doing it right the first time around, given all the iffys I read in this thread, or so thinks me. ;) Its a great mental excersize and cheaper with less reprocusions for the first timer. Ever wonder why many keep seeking out other folks for another year..............:cool: FWIW, I do like pioneers though, and support these missions.

[rvinson@cfl.rr.com]

Sal's Dad,
Thank you for the answers. They are pretty frighteneing for me. I haven't built a boat since I was 14 in 1964. Also, I still work 40 a week and have limited budget for a boat.
It's just that the RM is so darn attractive and that photo of Rob running in such skinny water standing up with that hat and all reminds me of days gone by when life was easier and it just grabs me. It might be that since I am recovering from last weeks back surgery I am on meds and maybe am not thinking straight.

I use a kayak to get into shallow water now and the thought of a boat with shallow draft that one can move around in is a delight. The charm and beauty of wooden boats is almost hypnotic and I think I am hooked from looking at Dad's Wooden Boats magazine.

Is there a simple shallow draft boat that would suit me better? I wouldn't buy or build it if it did not look nice. I really didn't want to go with an outboard and would prefer to have the prop protected by a tunnel design. However the tunnel seems very difficult to build in wood. How does one bend the wood at that tight of circumference? .

I am going to join the Yahoo group and see the discussion of the RM there. Thanks you for that knowledge.

Regards,

Bob in Florida

[erster]

Is there a simple shallow draft boat that would suit me better? I wouldn't buy or build it if it did not look nice. I really didn't want to go with an outboard and would prefer to have the prop protected by a tunnel design. However the tunnel seems very difficult to build in wood. How does one bend the wood at that tight of circumference? .

I am going to join the Yahoo group and see the discussion of the RM there. Thanks you for that knowledge.

Well with today's modern materials all you need is some modern materials, a form, some experience with working with some structual glass and you can build a tunnel and incorporate it into a plywood build for any hull. I know this is a bit taboo for this boat construction, but not out of the question. As far as the Yahoo group, I attempted about a year ago to swap banter and did not have much response in gaining much in the way of feedback. As of today, most of what I have read has been the swapping of ideas and chatter about people amazed at the shallow draft of the boat.

There are many other plans that deal with flats boats and the nature of their drafts for your expected needs I am assuming for redfish gunkholing if you want to go that way in the beginning. These plans can give you some knowledge and some added learning before you wing it on your own, in my opinionated opinion here.

This is a firend's hull that incorporated an air cooled engine and adapted a hurst gearbox to it after building an adapter plate.
http://img.photobucket.com/albums/v356/Bateau1/sticksteering.jpg

If you look really close, you will see daylight through the glass. This is easy to accomplish even using thin layups of veneers of plywood over a dummy mould of wood laying flat on a table.
http://img.photobucket.com/albums/v356/Bateau1/tunneldrive.jpg

http://img.photobucket.com/albums/v356/Bateau1/paintedtunnel.jpg

[JimD]

Three mil occoume plywood is remarkably bendy. I don't see anything in the lines of RM or in these photos that it couldn't handle with a little coaxing, a couple layers laminated with epoxy.

[erster]

This one has an old cast iron 10 HP Briggs and Stratton. I put on a Bedford in and out box which disengages the drive shaft. There is no reverse

This is listed on the gear that is on the link of the boat for sale in Vancover.

[Ron Williamson]

If you want shallow,but no tunnel,look here;
http://www.disappearingpropellerboat.com/history.html
R

[windmill4048]

[quote=Sal's Dad;1507574]Nobody has ever built Atkins' Rescue Minor. Robb White confused things quite a bit, by building an Atkins-style Tunnel-Stern Skiff of his own design, and naming it Rescue Minor. There have been rumors of RM's, but I have been asking, and for a few years asserting that there are none existing, and nobody has stepped forward to claim otherwise.

There are several now in progress. (mine included)

My Rescue Minor is in the final stages of construction. Final painting, final assembly of the drive train and sea trials are all that remain.

I expect to be on the water within three weeks.

[Tylerdurden]

[quote=Sal's Dad;1507574]Nobody has ever built Atkins' Rescue Minor. Robb White confused things quite a bit, by building an Atkins-style Tunnel-Stern Skiff of his own design, and naming it Rescue Minor. There have been rumors of RM's, but I have been asking, and for a few years asserting that there are none existing, and nobody has stepped forward to claim otherwise.

There are several now in progress. (mine included)

My Rescue Minor is in the final stages of construction. Final painting, final assembly of the drive train and sea trials are all that remain.

I expect to be on the water within three weeks.

You know we have questions?

[Tylerdurden]

Here are my thoughts on the subject of Rescue Minor and in general on tunnel drives in general. I still think Robb did it just "because" in my opinion but did it with a fair amount of experience in messing with boats. A tunnel drive with any inboard was and still is used for a boat when its primary use is shallow draft being the main use with a small craft. The net amount that you gain by using a tunnel is so little for the occasional boat these days makes it just not worth the trouble in more than one case these days when building a small hull out of anything that resembles wood.

Incorporating into a build hydraulics or even slip drive gear boxes was fine in the commercial industry. But for a pleasure craft the builder needs to spend more time and in some cases money and hassle for what it actually nets out in your favor. Another huge issue is down the road for any resale of the hull. A tunnel drive system is completely different than the tucked stern which was also incorporated in work boats and inboard engines with a shaft drive. In my opinion this is still the better of two evils if you are looking to minimize your draft with an inboard power system.

If you have never built a tunnel boat, you can build in a nightmare for handling if the tunnel is improperly designed and built into your hull. This renders your boat a bastard in almost all cases when in use.

Nothing is above doing and much easier to do it wrong than doing it right the first time around, given all the iffys I read in this thread, or so thinks me. ;) Its a great mental excersize and cheaper with less reprocusions for the first timer. Ever wonder why many keep seeking out other folks for another year..............:cool: FWIW, I do like pioneers though, and support these missions.

A+ Its really nice to agree with you.

[Sal's Dad]

Three mil occoume plywood is remarkably bendy. I don't see anything in the lines of RM or in these photos that it couldn't handle with a little coaxing, a couple layers laminated with epoxy.

RM's "chine" panels don't seem to be "developable". Close, but not quite.
Sal's Dad

[Sal's Dad]

I expect to be on the water within three weeks. In our neighborhood "on the water" might be possible now. "IN the water", on the other hand, can be a bit tougher for the next couple weeks...:rolleyes:

My RM is at the welder's, full of snow...
Sal's Dad

[Spokaloo]

Holy hell, that thing is STILL at the welders? Its been MONTHS!

E

[Tylerdurden]

I have been at this for over a year now and haven't started yet.
Kinda glad I took my time though I still have issues to sort out.
Been stuck on the kitchen rudder and the biggest question was flexing under load as the clearances are close to a 1/4" around the prop.
I had some 14# stainless rolled and we found that the deflection was to great so 11# seems the ticket. The rudder itself is actuated by a bimba cylinder driven by a steering pump so that wipes out the issues of the drive gears loading and the outrageous costs associated with having custom gears cut. Once the rudder has been assembled and tested we will go to town on the hull. The main reason for that is I don't have the space to tackle both the rudder and hull at the same time, also it was to damn cold to do any layups.
We are going to stick with Rob's original Idea and use a L type automotive belt for the drive and reduction. It will be direct and unable to unload and I am hoping that it will start readily with the rudder in a neutral position. If not its an easy mod to unload the belt for starting. Thats the status so far, I am curious to how others are doing with their designs in the water. If it turns out there are unforeseen problems I can do changes or abandon it altogether.
Its been fun so far as I decided to challenge myself with the rudder idea and I can adapt it to other designs in the future.

[F Fred]

I would question the choice if a diesel engine . A gas engine will be far lighter and far less costly to maintain.An Onan twin cylinder with 18 to 24hp is light , smooth and very reliable.Usually under $1000 NEW.

For a boat that might not see over 200 hours a year , the ability to merely shut off the engine , spray some fogging fluid down the cylinders , and remove the fuel , to burn in your car seems easy.

A diesel will usually have a long "out of service over 30 days"procedure that is time consuming and not inexpensive.

With no cooling water required , sand bar bashing , becomes lots easier.

F Fred

[Spokaloo]

Unfortunately fred, the design requires a diesel for another reason. The weight of that motor prevents cavitation in the tunnel, along with providing an extremely long service life as it will be a low rpm utilization.

E

[F Fred]

"The weight of that motor prevents cavitation in the tunnel, along with providing an extremely long service life as it will be a low rpm utilization."

As I understood the box keel the tiny hull would reach hull speed very early , and the stern wave that usually causes a displacement boat to squat at hull speed provides the water for the prop to work with.

The acceleration of the prop water helps lift the vessels stern , leaving a clean efficient wake.

All the props in the Atkins Sea Bright boats seem to only be half submerged at rest .

Load % and mean piston ft per second determines an engines life, not weather its gas or diesel.

LOVED the Blogg , what a great amount of effort!

PLEASE , when the boat is complete post a GPS /RPM comparison of the boats performance empty and with a dozen folks aboard. A weight/performance comparison would be very usefull, IF you can get an accurate weight from the ladies!;)

FF

[Spokaloo]

Fred, the tunnel can aerate with the shape of the hull when at light load if she doesnt sit on her lines. Atkin penned her for a specific weight, which if it isnt there will allow air into a small cavity formed on the forward side of the tunnel. I have a set of the plans, and as the bilge panels make their turn into a concavity, there are two small areas where air can enter. When at her lines, they are below the waterline. Yes, the prop is exactly half submerged (almost dead nuts on the shaft as drawn) but the propwash fills the cavity on spinning the prop. The static tunnel doesn't have a cav problem, its the inflow if shes light or heeled over.

E

[Sal's Dad]

I'm going to the Boatbuilders' Show in Portland this weekend, and will probably have Rescue Minor (aluminum) tagging along, if I can find parking.

Give me a call if interested in taking a look.

Curtis
207 650 323Five (mobile number)

[Tylerdurden]

I will keep an eye out for ya, I am picking up the rolled stainless for the rudder today.Just a little machine work left on it.
Soon as its done I am going to start lofting.

[Ricardo42]

Wes, I am interested in building a rescue Minor with the same setup that your father used. Have you got a photo that you can place on the Forum so that we interested paties can have a look? I live in Australia in a Lakes area and the shallow draught is very attractive

[cshire]

All these ideas of belt drives, hydraulic drives, maybe diesel electric, and other conversion/innovations are interesting.

However the consensus seems to be that additional weight may be needed to have RM sit on her lines properly with our lighter modern engines.

Why not stick with a tried and true Velvet Drive or similar inboard transmission? Direct drive Velvet Drives are just under 100 lbs and reduction drives are around 125-130 lbs. Used Velvet Drives can be found on e-bay and boat salvage yards for maybe $250.

They are fairly simple transmissions, parts for rebuild are readily available, etc. Why re-invent the wheel when a usable and affordable solution is already out there?

[Sal's Dad]

It's not about the weight - it is finding the appropriate gearing and geometry. RM needs a fast-turning prop, with a perfectly horizontal shaft, about 5" above the flat bottom. And a powerplant of about 20hp. I am not familiar with Velvet Drives - but it looks as though current models wouldn't work in this application.

Suggestions are welcome.

Sal's Dad

I got a little Hurth (current version is ZF10M) on EBay, but it's going to be tough getting the engine (Kubota 722) low enough to get the shaft positioned properly.

[cshire]

If you want your prop shaft to spin at 2000 rpm and your engine makes it's max torque at 2000 rpm and has a max rpm of 3000 you want a direct drive transmission - no reduction or overdrive. Any fine tuning is accomplished with the prop.

I don't have the full plans for RM but the lines drawing on the Atkins website appears to show the shaft at a shallow angle not untypical of inboard power boats. This should get the engin up off the floor a bit.

One option to mount the engine lower may be to modify the oil pan (and pickup if needed). Many powerboat applications use a different oil pan than automotive use to allow lower mounting of the Ford and Chevy V8 engines. For a Kubota you would probably need a custom fabricated sheet metal pan.

[Tylerdurden]

I am running a Yanmar in mine, in mock up the shaft is almost parallel.
I am using direct drive using a powerflex belt for reduction. As Wes says Robb White found he didn't need reverse and I have been chasing the dragon with my kitchen rudder idea. I am going to build conventional and leave in place where I can mount the kitchen rudder at a later date. I had some major issues with the rudder prototype so I will finish that idea later.

[pipefitter]

Where I launch my boat at,it is too shallow to put the outboard down to use reverse and I don't like sucking all the sand thru the water pump so I use a push pole to move the boat to deeper waters.I could see where you could easily get away without reverse.Airboats have no reverse either. I doubt you will miss it unless you launch from ramps with strong tides and then it's just getting handy with the boat hook upon returning.

[mcdenny]

Lots of folks use reverse for "brakes" when docking. Makes me cringe to watch.

[Clarksound]

I have thought about building the Rescue Minor but I needed to see some photos of the construction. I did run across a professional builder who has a pretty good website with pictures of the Rescue Minor. If anyone needs a visual of the construction of the Rescue Minor take a look at www.seaislandboatworks.com (http://www.seaislandboatworks.com) They have a pretty extensive photo gallery.

[Philip Maynard]

I see there are photo's of a model now on atkins site which I do not recall seeing in the past and it confirms their description:
"The form of the hull is simple and therefore comparatively easy to build using waterproof plywood planking"
http://boat-links.com/Atkinco/Photos/RescueMinor/index.html

With regard to "Nobody has ever built Atkins' Rescue Minor"

Atkins says he built many of these, "And added to these straightforward features one can rest assured that because I have perfected the design by slow development over many years and by the production of many boats of this particular model"
- did none survive?

[Spokaloo]

I know of one thats been built, has been used, and is being fine tuned now, trying to play email tag with the guy.

E

[kengrome]

... a professional builder has a pretty good website with pictures of the Rescue Minor at www.seaislandboatworks.com (http://www.seaislandboatworks.com)Well what do you know, it looks like there is a "genuine" Rescue Minor being built in modern times!

Robb White built something very similar of course, but he made his very light, he gave it softer chines, and he made some other changes too I suppose. Then people whined that his boat was not a "real" Rescue Minor ... but to tell the truth I don't know what that has to do with anything ...

If a boat has a tunnel-stern that is similar to the original Atkin plans, and if it works as efficiently as Robb White said his did, then who cares if it's a "real" Rescue Minor or not?

I'm designing one myself that is certainly not a real Rescue Minor, nor is it a Shoals Runner, nor is it a Tolman Seabright -- yet it has what I think are the best attributes of all these boats, and a few other features that should make it even better:


http://www.bagacayboatworks.com/linkfiles/xbb19/thumb/60006xbb19v07bottom1.jpg


This is just a preview, the rest of the images are here:

http://www.bagacayboatworks.com/linkfiles/xbb19/index.php

length = 19 ft 0 in
beam = 5 ft 9 in
draft = 6 in
waterline length = 16 ft 4 in
waterline beam = 4 ft 5 in
height at bowstem = 3 ft 0 in
height at midship = 2 ft 1 in
height at transom = 2 ft 3 in
displacement @ 6 in = 1000+ lb
displacement @ 12 in = 3000+ lb
displacement at flood = 7800+ lb

If I can keep the weight down to around 600 pounds or so for the hull and engine, this would meet my target design displacement of 1000 pounds for two people plus fuel -- and allow the boat to run full speed in 6 inches of water. With only one person onboard this boat will probably draw only 5 inches ... :)

[kengrome]

An Onan twin cylinder with 18 to 24hp is light, smooth and very reliable. Usually under $1000 NEW.I just found a web page that says Onan engines are no longer in production, so it looks like the only ones available any more are in used equipment.

[Tom Lathrop]

Well what do you know, it looks like there is a "genuine" Rescue Minor being built in modern times!

:)

The owners/builders of Sea Island Boatworks in Charleston, SC are friends of mine. I did not know they were building a Rescue Minor though. Rest assured that I will get the straight scoop from them about this boat and its performance.

[erster]

Tom, when Steve was here last week, he also stated that at the Perido [sp?]boat show this year there was a finished on exactly like the late Mr. White, built strip planked. But he state that the guy has never shared anything on any internet forum.

[Spokaloo]

Another REAL Rescue Minor:

http://i17.photobucket.com/albums/b65/fighterama2/normal_CIMG0696.jpg

E

[Sal's Dad]

"Bingey" afloat - in this picture with temporary 6hp power.
http://i122.photobucket.com/albums/o248/sals_dad/Bingeyafloat.jpg

About 8 or 10 kts, with 25 hp temporary power. Note water in well.
http://i122.photobucket.com/albums/o248/sals_dad/about8kts.jpg

Careened for finish work. (note Diablo at left - she misses the 25!)
http://i122.photobucket.com/albums/o248/sals_dad/CareenedB.jpg

The way life should be...
http://i122.photobucket.com/albums/o248/sals_dad/BowseatB.jpg

Anybody in the Bath, Maine area want to help me with sea trials? I'd like to get some photos at various speeds. There are significant performance issues (porpoising and loss of control over 12 kts!) that need some attention. I'll be mostly offline this summer, but can be reached at 2O7 65O 3235.

Curtis (aka Sal's Dad - see McCloskey's books...)


Just nobody ask what kind of wood it is!

[Sal's Dad]

I forgot to mention - the most disturbing incident so far was running up on a mud bank on a falling tide. With an outboard, the lower unit digs in and stalls, then you pull up the motor and row/push/pull (think "African Queen) back to deeper water. But I had run it up into 3" of water before it stopped, with the tide falling about 1/2" per minute. A few minutes of frantic efforts, then a 3 hour wait . . .

Makes you think twice about hot-dogging around in the shallows.

Sal's Dad

[kengrome]

Hi Sal's Dad,

It's GREAT to see your Rescue Minor pix! It looks like all your effort was a success. I see that you'll be offline most of the summer but maybe I will catch you before you leave cyberspace, and if not then perhaps you can reply and post some more news when you're online again.

I'm curious about the water level in your outboard well. In your second picture it looks like the water is only an inch or two below the top of the well. Am I imagining things or is this really how high the water gets in the well?

Your porpoising and loss of control issues may be the result of your temporary power system. If all that water is being sucked or pushed up into the well it seems like it might not lift the stern as effectively as it should. Once you finish the boat according to plans it will probably perform more like the way Robb White described his boat.

How much does Bingey weigh empty with no engine, did you have a chance to weigh her before getting out on the water?

Congratulations! :)

[Sal's Dad]

Ken, Yes, the water fills that well right up, at 12 kts it is full to the rail and streams out through the deck scuppers, despite maybe 2 square inches of scupper at the bottom of the transom. I'd guess the water gets 16" or 18" high, better than 20 gallons, with the motor and fuel tanks lashed on top, that puts maybe 350-400 lbs right aft. Even with this, the bow still pushes down if I try to go a bit faster. This is exciting - solid water up the bows, forced up into the gaps in the pipe rail, then streaming down in sheats from the inside of the rails. Meanwhile stearing gets wild, and the crew starts to panic...

There is a bit of "hogging" in the sheet metal, as a result of weld distortion. Before trying to fix that, I'll try sealing up the motor opening. The prop is pretty much right where the plans say, but the exhaust runs out through the center, so maybe that has an impact.

Weight of hull is about 550 lbs, and so far gear is pretty minimal. I have some heavy cargo to transport, maybe that will change the dynamics.

Sal's Dad

[Pericles]

As in most cases, there are additional designs to be considered when trying to create a craft for running safely in shallow waters. Some months ago, this company was brought to my attention and you may find some of their ideas inspirational. http://www.flatscat.com/

If nothing else, their videos are instructive and entertaining.

Regards,

Pericles

[Eric D]

any updates from those building these? Tom any news from your buddies who are building them?

Thanks