Guys this is not debatable
Crimping is only suitable for large diameter cable where soldering is not practical or for when a cable is TOO light to solder effectivly.
The rule of thumb from brodcasting is crimp signal and solder power. However heavy DC lugs to terminals such as battries Crimp (Professionally As said) more effectivly than Soldering unless industrial flow or potted solder is available.
Regardless of preference, metals expand/contract at different rates and crimping on light cables ie 4 or 5 amp etc is a bad idea period for something like your bilge pump wiring.
Correct method for soldering this would be to twist/twirl each end to avoid stray ends, then form a loop/ hook in each end, then tin them by applying the iron to the ends. select one and using a hellerman tri expander put a sutible hellerman sleave over one. interlock the two hooks and squeese for mechanical strenght then solder with the iron in the center just long enough to allow additional solder to flow into the hooks but not long enough to DRY the joint. when cool enough to touch, apply hellerman oil and slide the sleave
over the exposed joint. Then support the cable eaither side with P clips for ALL the usual practical reasons.
If You want an alternitive solution, purchase a std domestic junction box, strip the bilge wire ends and twist the paired ends before inserting into the brass and tighting the screw.(ie in from same side as opposed to in on one side and out the other) the advantage is akin to that of a professional crimp in that the screw squeeses the cores tight and the junction box will provide mechanical strenght, support and protection.
In absence of someone who REALLY knows how to solder or crimp, the Junction box Should prove the most robust of any DIY solutions