These were the strings shipped on the original UBass models. The name comes from a geological lava formation. Pahoehoes are solid polyurethane cord in varying circumferences. These range from a thick E to a much thinner G string.
Make sure you buy the UBass friendly strings which are the 20″ to 21″ scale versions. They are available in black or there are some coloured strings for those of you who are a bit more adventurous.
The Pahoehoe strings are long lasting and durable. They usually take a few weeks to completely settle down at tension. I assume this is due to the inherent stretchiness of polyurethane. You can reduce this by pre-stretching the strings before putting them on. I also find it necessary to trim and reinstall the D & G strings after a week. This prevents the amount of windings on the machine head from becoming excessive.
Aquila Thunderguts Strings
A more recent set of strings with a more secret formulation has come from the Uke string favourites Aquila. They are slighty higher tension than the Pahoehoes and feel harder to touch. Once installed and bought to tension, they settle down and hold tuning within a few days which is an improvement on the Pahoehoes. One distinct drawback of these strings is they are bright white and in my opinion look horrible.
I have tried a set of Thunderguts and found them reasonably playable until the strings starting sticking under my fingers Apparently this is a reaction to certain types of skin chemistry. I guess I’m unlucky. Apparently using some form of lubricant powder on the fingers is the answer but I have tried it. I didn’t really like the sticky Thunderguts and removed them and went back to the Pahoehoes. I think it’s just one you’re going to have to try for yourself.
Aquila Silver Rumblers
Aquila have bought out a new set of thankfully black strings which are supposed to expand on the positives of the Thunderguts. I haven't found a definitive answer on whether they inherit the sticking problem of their predecessors so I'll try them and find out. Currently I can't get them in the UK so it has to be mail order from the US.
Aquila Thunder Reds
The Thunder Reds sets: a unique look and a strong, consistent sound. Until now, it was necessary to increase a string’s gauge to reach lower frequencies. But increasing the string’s diameter also increases internal dampening. That makes the string less bright, less responsive and more muffled: the thicker the string, the duller the sound. Our revolutionary new approach —never introduced before us— changes the specific weight of the material, increasing it progressively to leave the gauge unchanged.
Taken from the Aquila website.
Aquila Thunder Blacks
I've never tried but here's what the manufacturers have said about them. Having them in black has got to be a positive though.
Thunderblack is a special very elastic and dense material developed by us in our headquarter that assure superior performances over the common polyurethane and silicon rubber bass strings available in the market. Thundergut assure fast and stable intonation; no sweet finger’s slip on the strings, powerful performances.
Taken from the Aquila Website.