How in the world do you pour this much foam and set the tanks down in time? I ordered sum pourable foam today to play around with but whats your suggestion on mounting these tanks??

you set the tanks. Then pour it around the tanks in several batches of foam. I did it on my 27 Magnum.

make sure you have a hold-down strap or piece of wood across the top to keep the foam from pushing the tank up.

Its got to have foam under it because of the steps which is a huge area to cover with foam. I dont have a better pic but some of it is ~6" thick

what he said i do the same, pour in smaller batches. Let each one expand all the way till you start the next. You have to be careful that schit will do some damage if you put to much in a close cavity.


Dan, what Magnum do you have? I am starting a resto of one for my self. Currently i have a Klem Gem Sport copy but have decided to look for a real Mag. I have a pair of Arneson 6's and getting a pair of LS's built for it.

do as they said and use small batches or really bad things happen. years ago at a buddy's marina some guy thought it would be a good idea to fill the front of his 18 foot boat with foam so he drilled a small opening to pour it in. he mixed a couple gallons of it and dumped it in all at once. it made a heck of a noise when the deck broke loose and lifted a foot off the hull.

http://www.yachtsurvey.com/fueltank.htm

good food for thought.

Some other things to consider......
Make sure the cavity is well sealed. For instance, early (pre '94) Donzi Classics had a 3/4" PVC pipe set in the fore and aft tank bulkheads for draining the bow. Donzi installed the pipe in double sided rubber tape and it always allowed water into the compartment. The tanks were never finished in any way and corroded through. This may be a common problem in a lot of boats.
The solution is to seal the drain pipe in epoxy, and coat the tank w/coal tar epoxy. The new tank will probably last 50 years.
There can be a lot of pressure generated by the expanding foam. I usually temporarily bolted some 2" X 2" X 1/4" angles onto the outside of the top of the stringers so that it's easy to clamp some 2" X 4" lumber across the tank top.

The method outlined in the article listed above is fine if you don't mind giving up 30% to 50% of your tank volume.
Also, it's very difficult if not practically impossible to support a Vee shaped belly tank in deep Vee hull because the tank section is constantly changing. Foam is a great solution if the tank is properly coated.