Model Boat Mayhem

Mess Deck: General Section => Model Boating => Topic started by: MvModeller on November 17, 2018, 07:42:45 pm

Title: Ply Keel has a slight bow
Post by: MvModeller on November 17, 2018, 07:42:45 pm
Hi there


I have just started building my ship, So far have built the building board, and cut out the ply keel.. I have come to size the keel up on the building board along the center line, but the keel isnt truely straight? Will this be a mayjor problem?


The keel is about 1.2m long. And the center is about 5mm away from the center line. (to gauge the bow)


Best regards
Mv
Title: Re: Ply Keel has a slight bow
Post by: dougal99 on November 17, 2018, 08:50:49 pm
What thickness is the ply keel? Are you building plank on frame or hard chine? With POF if the keel is not too thick the frames should hold the keel straight, reinforced by the planks. Hard chine hulls tend to have fewer frames and it may be difficult to keep the keel straight. I try to store my sheet ply flat as standing it on end causes thinner sheet 6mm or less to bow.
Title: Re: Ply Keel has a slight bow
Post by: MvModeller on November 17, 2018, 09:05:06 pm
The keel is 6mm thick.. the build is Plank on frame.


Ive been storing the keel on the building board flat since ive noticed a bow. Once its fixed to the building board and the frames are in place along with the stringers.. do you think it will be okay? Bit of a novice.. first build so... not to sure what to expect...
Title: Re: Ply Keel has a slight bow
Post by: Onetenor on November 17, 2018, 11:54:17 pm
Soak in hot water . Preferably with some ammonia in but watch out for fumes. do it outside. Then lay it flat and place weights on it and allow to dry for a week Old batteries make good weights. A car battery best. Works every time. Good luck.
Title: Re: Ply Keel has a slight bow
Post by: John W E on November 18, 2018, 09:43:01 am

hi there ; if all of the frames are true to the centre line of the building board, with the slots for holding the keel cut true in the frames, the keel should be true to the centre line of the building board - so - any 'bowing/twisting' should be pulled true.   one thing  I do is either side of the keel flush with the tops of the frame, is, I add a piece of 1/4 inch timber either side of the keel, glued into place, to give the first plank a better area to be glued upon.   Have a look at this build.


https://www.modelboatmayhem.co.uk/forum/index.php/topic,13888.msg133137.html#msg133137 (https://www.modelboatmayhem.co.uk/forum/index.php/topic,13888.msg133137.html#msg133137)


john
Title: Re: Ply Keel has a slight bow
Post by: ChrisF on November 18, 2018, 11:36:58 am
Unfortunately, sheets of ply are rarely nice and true, especially in a length long enough for the keel. As John says, if the frames or keel are fixed down to the building board it will be pulled straight. 5mm in the middle of that length is no problem.

Again, as John says, fix some doublers either side of the keel (the plans may call for these anyway) and once the hull construction is complete it will retain it's trueness.
Title: Re: Ply Keel has a slight bow
Post by: dreadnought72 on November 18, 2018, 03:18:14 pm
At these scales the strength is really in the hull woodwork, not so much in the keel. (Has ANY model boat broken its back?) Ensure the keel is straight while planking up, and all will be good.


Andy
Title: Re: Ply Keel has a slight bow
Post by: MvModeller on November 18, 2018, 04:50:24 pm
Cheers guys.. a sigh of relief. Many thanks as always..