Battery, solar panel and a pump or a cover
Perhaps limiting the amount of water coming in may help, say by using a boom tent or a boat cover. But you might consider installing a battery and a bilge pump. You have the option of using solar power to recharge the battery or take it off the boat to charge it. A solar panel might not fully meet the demand of the pump but it would depend on the size of the panel and the amount of rain you get. A fairly small battery (like a group 26 or 51) with a handle on it is pretty manageable. I have had good luck with 2 flexible 35W solar panels on my boat but there not cheap. I would think a boom tent in combination with a battery and a single 35W panel would do the job.Hope this helped,Al M