INVESTING STRATEGY

I have an apartment that is partly an investment property and partly a second home. We live in ourselves half the year and from now and we make it available for short term rental the other half year (not AirB&B, but the same sort of deal). We have a mortgage on the property, but have a balance in an offset account to match the amount remaining on the loan so we are no longer paying interest. Would it make more sense to drain the offset account and invest in more shares? Things to consider: * I understand that we can claim the interest against tax for an investment property, but I am not quite sure how this works when the property is only 50% for investment purposes — does that mean we can claim 50% of the interest? * We are both working full time so paying the interest wouldn’t be a problem even if the rental income wasn’t there; * I am in a very good defined benefit superannuation scheme that will cover our needs in retirement, so our risk tolerance is fairly high; * Still, if I do this and then the share market crashes while interest rates rise, I will regret the decision.