Bourbon Barrel Aging with Oak Spirals and Boil Time

[Guinjasp]

I am a fairly new brewer and have been experimenting with medium oak spirals rum and bourbon soaked on a few batches. My latest venture is an imperial stout that I will be adding spirals that have been soaking in Makers Mark for over a year. My goal is a big beer that is thick chewy and boozy.
A local craft brewer recommended that I extend the boil from 1 hour to 3 to thicken up the recipe and this is new territory.
Should I tweak my water and or ingredients to compensate for boil off?
Also when a drop hop the spirals after fermentation how long should I leave them in?
i am using a Grainfather G30 220v

 

[JohnSand]

I think you should adjust your water or you will end up with higher gravity.
When I have used oak I judge by tasting.
Keep us posted.

 

[Hoppy2bmerry]

If you want thick and chewy drinking stout increase some caramel malts I wouldn’t boil any beer for 3 hours, adjust the recipe, then perhaps do a 90 min boil. No need to waste energy when the recipe can get you there.

 

[Bobby_M]

The higher the target OG, the lower the inherent mash/lauter efficiency so planning for a longer boil will get some of that efficiency back (not time efficiency of course). For beers over 10% ABV I go to a 2 hour boil.