Surely, on island plates map everyone should get Shipbuilding very early (although not necessary belline). However, that's only 125 science with both eurekas, compared to 1215 science to reach Squire Rigging with the same eurekas. This means you could get both embarkation AND srordsmen for 1/5 of the Squire Rigging science. Alternatively, if you don't want to rely on Iron, you could beeline Military Tactics and Shipbuilding getting embarked Pikemen for still 1/2 of the Squire Rigging tech cost, plus getting things like Campus and Commercial District along the way. Even on Island Plates there are tonns of possibilities how to spend this huge pack of science effectively. Although I agree, in some cases beelining to Frigates on sea-based maps could be worth it, but it's surely doesn't look imbalanced. EDIT: And just as some rough planning. Consider what: - Pottery and Writing will unlock Campus, which will surely compensate the techs spent on them. - Astrology and Celestial Navigation together, even without eurekas, cost less than Cartography eureka you could trigger with them. So, the most effective "beelining" for Frigates looks like 8 techs, not 4. Finally, Frigate is 280 production and 5 gold maintenance. If you want to actually have Frigates, you need at least techs to improve resources (+2-3 techs), much better if you have Commercial hub and Industrial Zone.