Cookies used in this website are gluten free, wheat free and dairy free. By using this website you agree to our use of cookies. More Info
Guest
Login Below
Join Us On Social Media!
   
Get The Model Boats App!
Apple App Store
Android app on Google Play


Help Support This Website
£
or enter custom amount

(Non Contributor)

Help support this free
website and donate.



£285 a year is needed to keep the website and apps online. Please consider donating £5 or more to help towards these fees.
All donations are securely managed through PayPal. Amounts donated are not published online.

Many thanks for your kind support.

Model Boats Website Team


Donation History
December 2018: 4 people
November 2018: 11 people
October 2018: 9 people
September 2018: 13 people
August 2018: 5 people
July 2018: 8 people
June 2018: 8 people
May 2018: 7 people
April 2018: 24 people
March 2018: 11 people


Unique Visitors This Month

Website Members

Terms and Conditions
Privacy Policy
Advertising
Contact


Model Boats Website
Active Users (21)
Login or Register
To Remove This Ad

Login or Register
To Remove This Ad
>> Home > Forum > Building Related > Brixham trawler IBEX
Brixham trawler IBEX
(1597 views)
Author Message
bellman1942
(Sub-Lieutenant)





Forum Posts: 13
11th Oct 2017 10:09  
>> Permalink
mdlbt.com/34363

I`m building a Brixham trawler IBEX
Anyone know how much ballast is needed for a scratch built hull would it be wise to use a bulb on a fin or along lead keel

RNinMunich
(Fleet Admiral!)





Forum Posts: 2484
11th Oct 2017 10:29  
>> Permalink
mdlbt.com/34366

Hi bellman, (from Doug BELL😉)
This is another 'How long is a piece of string question'!
Only way to find out is to build it, and do a payload test.
Put weight in it until it floats to the waterline and upright and stable.
I use chunks of lead and lead balls (fishing weights).
Weigh the lead. Easiest way is to weigh the empty hull first, then again with 'payload'. Difference is your payload weight for the hull, including all equipment, decks, superstructure etc.
Before you glue any other parts to the hull weigh them and subtract from the payload test weight as you go.
When compete you should then know how much weight you have left available for equipment.
Weigh the equipment; motors, shafts, electronics, batteries etc.
Anything 'left over' is the ballast you need.
Try to fit it inside as low as possible, the lead balls are good for final trimming. When all is correct simply pour a little resin over them to hold them in place.
Only time I fitted ballast outside, a long steel bar keel, was on my U26 sub. But then U Boats had such an emergency 'drop keel' so it looked 'Right'! Happy building, Doug 😎


Young at heart - slightly older in other places 😉 Cheers Doug
cenbeth
(Admiral)





Forum Posts: 171
11th Oct 2017 10:31  
>> Permalink
mdlbt.com/34367

Hi

With my sailing pilot cutter Cariad, when the hull was largely complete I put her in the bath an put weights in until the waterline was reached. I then weighed the weights. I then tried to make the bulb keel slightly lighter to allow for trimming.

I would make provision for the bulb keel at an early stage of construction. I didn't do this and it was a right pain!

Good luck

Edward

RNinMunich
(Fleet Admiral!)





Forum Posts: 2484
11th Oct 2017 10:36  
>> Permalink
mdlbt.com/34369

Hi, found some interesting info on this boat, including hi res pics of the building of a model. Sample attached.
http://www.modelships.de/Trawler-IBEX/Trawler-IBEX_eng.htm
😎


Attached Files - Click To View Large


Young at heart - slightly older in other places 😉 Cheers Doug
RNinMunich
(Fleet Admiral!)





Forum Posts: 2484
11th Oct 2017 10:46  
>> Permalink
mdlbt.com/34370

Here a video of such a model sailing-
https://www.youtube.com/watch?v=jXfI2qIL5Ew
Lovely boat 👍


Young at heart - slightly older in other places 😉 Cheers Doug
bellman1942
(Sub-Lieutenant)





Forum Posts: 13
11th Oct 2017 14:41  
>> Permalink
mdlbt.com/34378

Many thanks all still wonder if fin and bulb is better than internal ballast🤔

cenbeth
(Admiral)





Forum Posts: 171
11th Oct 2017 15:33  
>> Permalink
mdlbt.com/34379

A detachable bulb keel will result in a more stable sailing experience. The further away the weight is from the centre of buoyancy the better.

RNinMunich
(Fleet Admiral!)





Forum Posts: 2484
11th Oct 2017 15:36  
>> Permalink
mdlbt.com/34380

Maybe bellman, but wouldn't it look a bit daft? 🤔
Hide it under yer raincoat 'til it's in the water 😉
Happy building, and even Happier sailing👍


Young at heart - slightly older in other places 😉 Cheers Doug
onetenor
(Fleet Admiral!)





Forum Posts: 462
16th Oct 2017 13:54  
>> Permalink
mdlbt.com/34552

A Brixham trawler with a bulb and fin keel would look rather odd though wouldn't it ?👍

RNinMunich
(Fleet Admiral!)





Forum Posts: 2484
16th Oct 2017 14:55  
>> Permalink
mdlbt.com/34556

Exactly my thought! 😲
There must be a better way to ballast it.


Young at heart - slightly older in other places 😉 Cheers Doug
Dave M
(Fleet Admiral!)





Forum Posts: 1527
16th Oct 2017 15:11  
>> Permalink
mdlbt.com/34557

Hi Bellman
My Club sail several similar boats as well as an Ibex. They are all fitted with detachable keels which are fitted prior to sailing but can be removed for transportation and display.
Our sailing waters are large and exposed and without the keels the models would not be able to be sailed. On the water the keels can not be seen.

I tried a long keel on my Cariad and it was not a success as the keel tended to keep the model in a straight line. I now use a detachable bulb keel.

The amount of lead will depend on your model and its overall weight. The bulb keels are a fibreglass moulding that we fill with lead to bring the model to waterline after inserting fore and aft threaded rod into the bulb. You will need to have holes in the keel to let the rods thro and long enough to be above the waterline. I fit a plastic tube and wood support inside. A washer and nut hold the keel in place. Before filling with Resin weigh the resin in the tin and remove that amount of lead from the bulb. Once set I use silicon to make a good seal between the bulb and hull and which remains attached to the bulb.
Attached are pics of my Cariad.


Attached Files - Click To View Large


Live long and prosper

Dave
bellman1942
(Sub-Lieutenant)





Forum Posts: 13
26th Oct 2017 08:11  
>> Permalink
mdlbt.com/35004

Many thanks everyonefor the various advice I`ve decided on a bulb fin keel, when requesting advice on keel weight I should have mentioned the hull is 42in lg this was an oversight😋, I`m now drg.shadows from the plan quite a laborious task but interesting.
bellman

sam
(Petty Officer)





Forum Posts: 7
11th Nov 2018 12:36  
>> Permalink
mdlbt.com/47934

Hi everyone, just hoping someone still reads this blog. I am just about to start building Cariad and have decided to take advice from this blog, and fit a detachable keel. This is my second build and first fiberglass hull so being careful thinking it through.
it makes sense to design in the detachable keel before fitting the deck but clearly I can only measure the ballast - weight and position - once the boat is nearly complete. So id welcome some idea of the position of the false keel so that I can fit a tube now, and build the keel itself later. Anyone able to advise?🤔

cenbeth
(Admiral)





Forum Posts: 171
11th Nov 2018 16:13  
>> Permalink
mdlbt.com/47940

Hi Samnewbie
I have a Cariad which is wooden hulled at twice scale. I decided to use a false keel but as I bought the hull completed needed to retro-fit one. I agree with you! If you can fit the tube as early on as possible it will make life a bit easier. My keel needs to be about 12kg and the tube is a couple of inches behind the mast. I am still trying to cast the keel; I'm now on my fourth attempt!

I have calculated the keel weight and plan on it being about 1kg lighter than need be. This will allow me to finely trim the boat up once complete.

Good luck with yours.

Edward

sam
(Petty Officer)





Forum Posts: 7
11th Nov 2018 18:32  
>> Permalink
mdlbt.com/47943

Edward

Thanks - just one question, if your model is twice scale does this mean my tube should be about one inch behind the mast?

I aim to complete the boat before testing the weight of ballast needed then like you, allocating most to the keel and some to 'trimming'

Sam

cenbeth
(Admiral)





Forum Posts: 171
11th Nov 2018 18:49  
>> Permalink
mdlbt.com/47944

Hi Sam,

I guess so. If you want to be technical I suppose you need to think where your centre of gravity is, and where your centre of effort is from the sails etc.

Are you going to cast the keel or make it up?

Edward

sam
(Petty Officer)





Forum Posts: 7
12th Nov 2018 06:45  
>> Permalink
mdlbt.com/47964

Edward,

I'm going to cast a bulb which gives me some tolerance in positioning it on the keel to help with the final trim. Probably make the keel from two sheets of balsa with a central threaded rod screwed and epoxied to the bulb. But that's for a later stage, right now I want to build the shaft into the hull before fitting the deck.

Are you fitting an auxiliary motor? if so what sort of motor is most suitable?

Quite looking forward to starting but likely to hafe to wait until after Christmas - work intervienes

Thanks

Sam

cenbeth
(Admiral)





Forum Posts: 171
12th Nov 2018 09:45  
>> Permalink
mdlbt.com/47965

Hi Sam,

Yes, a Monoperm Super I think it is. It is only small as I reckon the original would only have had a small motor.

I had issues with getting the rudder to work because the rudder shaft is at an angle. Another thing I'm anticipating is the size of the rudder; it may need to be increased in size.

I think that thinking how problems can be overcome is half the fun!

Edward

sam
(Petty Officer)





Forum Posts: 7
12th Nov 2018 11:17  
>> Permalink
mdlbt.com/47968

Edward,

Yes - thinking out problems is half the fun😊

My first build was a Vic Smeed Starlet - just completed. Pretty straight forward but I over engineered it to try out some ideas - thinking the ideas through was great fun.

So although I will not start the Cariad until January I'm trying to explore problems now. The angle of the rudder shaft is one that I think I have a solution to. Take it right through the deck then put a handle onto it, hinged at the shaft so that it does not rise and fall as it is turned. Then a Bowden cable from each side of the cockpit to power the steering. I will enjoy building a mock up and trying it out!


As to the rudder, I am thinking of a detachable extension - downwards.

I'm also thinking about placing the prop to one side - perhaps more authentic but also well clear of the rudder.

One thing that I'm still thinking through is the access hatch. I see some builders move the dingy to the centre and create a hatch here but I like the clean decking on the original, with the dingy to the side. A hatch to the side would work for everything but the top screw for the detachable keel. Some more time dreaming up a solution.


Thanks


Sam

steve-d
(Lieutenant)





Forum Posts: 45
12th Nov 2018 13:09  
>> Permalink
mdlbt.com/47970

You don't have to think too hard about the keel position at this time as the bolt does not need to be central to the length of the keel. Just choose a rough position and do your hole in the hull.
Later when you know more about how much weight you need and where it needs to be positioned you just make the keel to suit the rod position.

Steve

sam
(Petty Officer)





Forum Posts: 7
25th Nov 2018 16:09  
>> Permalink
mdlbt.com/48326

Hi again,

To remind you - I'm about to start a build of Cariad - about a meter long fiberglass hull made by Chris Wynn-Brown. Selecting the auxiliary motor I'm looking at a m500 but any thoughts about the prop used. Thinking 2 blade fairly small, 25mm. Not needed for speed, just to get to shore if the wind dies. And originally auxiliary motors/props would have been small. Does this sound right? Sam