as Colin pointed out the use of sand is a good idea but if you can not achieve the weight you need than you can substitute lead shot for the sand as it is heavier.
My tug uses 18 pounds of removable ballast and weighs in at 45 pounds when trimmed out. I use the same approach as Cashrc uses and add the weight when the boat is in the water.

The Taucher Wulf I built last year needed about 11 pounds of ballast to sit in the water properly. I added about 3 pounds aft in the form of bb’s secured by ca and coated with epoxy. At that point the boat weighs about 7 pounds plus. I bought a cheap set of ankle weights from Amazon that used removable 1 pound weights..they are small bags filled with sand. I taped them up into 2 pound weights. The boat is stored without those weights, pondside I install battery (5000mah lipo) and 4 of the weights each side of the batter tray and fwd towards the bow. Works great, and I don’t have to lug a 16 pound boat everywhere.
The Kalle I just built uses bb’s aft, several pounds of loose bbs in doubled plastic bags, and I still added another pound in lead split between fore and aft.

I forgot to mention one of the reasons I like to use ballast in a bag and do not glue it in place is if your boat needs a lot of ballast and/or it is heavy than you can easily remove the ballast bags for transporting.

One method I use is freezer bags with kids play sand in various weights starting with 50 and 100 grams, then 200 grams followed by 500 grams .
Then I can rearrange in the hull as needed. I label them by weights and keep in a big wine bucket. A couple of my larger models need 15kg. So having it in small packs cuts down on heavy lifting.
It also molds to the hull interior shape very well.
Cheers Colin.

Thank you. I agree. I'm always one for saving money.

Greg 👍

Hello Len,

Thanks for the suggestion. A very good idea. I'm not sure where to get the BB shot or pellets from so I'll have a look on eBay. I do also go fishing so I suppose I could use the pellets that are used to weight the line and fishing floats. I think the only difference is that the fishing shot or pellets have a split in them so the can be crimped to the fishing line.

Greg 👍

Hi Greg,

I think all the various responses to your post conclusively show that many model boaters are looking to save both time and money at every opportunity.

Also almost all expensive commercial ballast is only available by post or internet order. The resulting hefty freight changes will boost the delay and cost even further!

With best wishes Dr John F. Leeds and Bradford BBC. 🤔🤔🤔

any of the suggested ideas will work but if you you use the loose shot like BB's or shot gun pellets I would recommend putting them inside a used sock and then placing the socks around the interior of the boat and adjust both the amount of weight and locations of the socks until you are happy with the results. At that point you can remove the socks, pour in some glue, like carpenters glue, and then place the socks into the hull and let them setup while in place and thus achieving the shape of the hull. If you want to make sure the socks do do glue themselves to the boat just put a layer of waxed paper between the sock and the hull before you place the sock in place. Without the waxed paper the socks may glue themselves to the hull although I am not sure about this.

Thank you to all that have posted replies. Interesting reading and very good tips. Interesting to see that no one has used a commercially made modelling product to do the job.

Thanks again.

Greg 👍

I generally use lead, often old sheet lead that previously served as roof flashings. Where there is access I have poured in cement mortar , made a mould from it, then cast the lead and fitted it, usually with some adhesive or silicone to hold it securely. There is no reason you shouldn't just leave the mortar in place but not being as dense as lead it will occupy more volume to achieve the same weight. Another method I have used is to cut the lead sheet into very small chips, then pour them into place. It is a bit time consuming, but for a small boat with difficult access it has worked well. This may not be as convenient as pouring in lead shot (or the current day equivalent), but a great deal cheaper, and it does not shift around. If you need to acquire lead sheet you could ask a builder for some old flashings, try a scrap merchant, or pay top price from a builders merchant.😊