diff --git a/src/lib/commands/prod.c b/src/lib/commands/prod.c
index 16b234fd..bdec10e8 100644
--- a/src/lib/commands/prod.c
+++ b/src/lib/commands/prod.c
@@ -71,7 +71,6 @@ prod(void)
     struct pchrstr *pp;
     double p_e;
     double maxr;		/* floating version of max */
-    double level_p_e;
     double prodeff;
     double real;		/* floating pt version of act */
     int work;
@@ -228,15 +227,7 @@ prod(void)
 	/*
 	 * production effic.
 	 */
-	if (pp->p_nlndx >= 0) {
-	    level_p_e = natp->nat_level[pp->p_nlndx] - pp->p_nlmin;
-	    if (level_p_e < 0.0) {
-		level_p_e = 0.0;
-	    }
-	    level_p_e = level_p_e / (level_p_e + pp->p_nllag);
-	} else {
-	    level_p_e = 1.0;
-	}
+	prodeff = prod_eff(pp, natp->nat_level[pp->p_nlndx]);
 	/*
 	 * raw material limit
 	 */
@@ -257,15 +248,9 @@ prod(void)
 	 */
 	max = (int)(work * p_e / (double)unit_work + 0.5);
 	act = min(used, max);
-	/*
-	 * some things are easier to make..  food,
-	 * pet, etc.
-	 */
-	act = (int)(((double)pp->p_effic * 0.01 * (double)act) + 0.5);
-	max = (int)(((double)pp->p_effic * 0.01 * (double)max) + 0.5);
 
-	real = dmin(999.0, (double)act * level_p_e);
-	maxr = dmin(999.0, (double)max * level_p_e);
+	real = dmin(999.0, (double)act * prodeff);
+	maxr = dmin(999.0, (double)max * prodeff);
 
 	if (vtype != 0) {
 	    if (real < 0.0)
@@ -275,15 +260,12 @@ prod(void)
 	    real = dmin(real, ITEM_MAX - there);
 	}
 
-	if (level_p_e != 0) {
-	    take = real / level_p_e;
-	    mtake = maxr / level_p_e;
+	if (prodeff != 0) {
+	    take = real / prodeff;
+	    mtake = maxr / prodeff;
 	} else
 	    mtake = take = 0.0;
 
-	take = (double)take / ((double)pp->p_effic * 0.01);
-	mtake = (double)mtake / ((double)pp->p_effic * 0.01);
-
 	cost = (int)(take * (double)pp->p_cost);
 	if (opt_TECH_POP) {
 	    if (pp->p_level == NAT_TLEV) {
@@ -379,7 +361,6 @@ prod(void)
 	}
 
 	pr(" %-5.5s", pp->p_sname);
-	prodeff = level_p_e * (double)pp->p_effic * 0.01;
 	pr(" %.2f", prodeff);
 	pr(" $%-4d", cost);
 	for (i = 0; i < 3; i++) {
diff --git a/src/lib/update/produce.c b/src/lib/update/produce.c
index 5094ea14..20b70b9b 100644
--- a/src/lib/update/produce.c
+++ b/src/lib/update/produce.c
@@ -59,9 +59,9 @@ produce(struct natstr *np, struct sctstr *sp, short *vec, int work,
     register struct pchrstr *product;
     int vtype;
     double p_e;
-    double level_p_e;
+    double prodeff;
     s_char *resource;
-    int output;
+    double output;
     int actual;
     int unit_work;
     int item;
@@ -101,27 +101,23 @@ produce(struct natstr *np, struct sctstr *sp, short *vec, int work,
 	material_consume = worker_limit;
     if (material_consume == 0)
 	return 0;
-    level_p_e = 1.0;
-    if (product->p_nlndx >= 0) {
-	level_p_e = np->nat_level[product->p_nlndx] - product->p_nlmin;
-	if ((level_p_e < 0.0) && (!player->simulation)) {
-	    wu(0, sp->sct_own,
-	       "%s level too low to produce in %s (need %d)\n",
-	       levelnames[product->p_nlndx], ownxy(sp), product->p_nlmin);
-	    return 0;
-	}
-	level_p_e = level_p_e / (level_p_e + product->p_nllag);
+    prodeff = prod_eff(product, np->nat_level[product->p_nlndx]);
+    if (prodeff <= 0.0 && !player->simulation) {
+	wu(0, sp->sct_own,
+	   "%s level too low to produce in %s (need %d)\n",
+	   levelnames[product->p_nlndx], ownxy(sp), product->p_nlmin);
+	return 0;
     }
     /*
      * Adjust produced amount by commodity production ratio
      */
-    output = roundavg(product->p_effic * 0.01 * material_consume);
+    output = material_consume * prodeff;
     if ((vtype == 0) && (!player->simulation)) {
-	levels[sp->sct_own][product->p_level] += output * level_p_e;
+	levels[sp->sct_own][product->p_level] += output;
 	wu((natid)0, sp->sct_own, "%s (%.2f) produced in %s\n",
-	   product->p_name, output * level_p_e, ownxy(sp));
+	   product->p_name, output, ownxy(sp));
     } else {
-	if ((actual = roundavg(level_p_e * output)) <= 0)
+	if ((actual = roundavg(output)) <= 0)
 	    return 0;
 	if (product->p_nrdep != 0) {
 	    if (*resource * 100 < product->p_nrdep * actual)
@@ -230,3 +226,28 @@ materials_charge(struct pchrstr *product, short *vec, int count)
 	vec[item] = n;
     }
 }
+
+/*
+ * Return level p.e. for product PP.
+ * Zero means level is too low for production.
+ * LEVEL is the affecting production of PP; it must match PP->p_nlndx.
+ */
+double
+prod_eff(struct pchrstr *pp, float level)
+{
+    double level_p_e;
+
+    if (pp->p_nlndx < 0)
+	level_p_e = 1.0;
+    else {
+	double delta = (double)level - (double)pp->p_nlmin;
+
+	if (delta < 0.0)
+	    return 0.0;
+	if (CANT_HAPPEN(delta + pp->p_nllag <= 0))
+	    return 0.0;
+	level_p_e = delta / (delta + pp->p_nllag);
+    }
+
+    return level_p_e * pp->p_effic * 0.01;
+}
diff --git a/src/lib/update/ship.c b/src/lib/update/ship.c
index aaace64e..9df01894 100644
--- a/src/lib/update/ship.c
+++ b/src/lib/update/ship.c
@@ -168,13 +168,18 @@ upd_ship(register struct shpstr *sp, register int etus,
 		/*
 		 * take care of oil production
 		 */
-		oil_gained = roundavg((sp->shp_item[I_CIVIL] * etus / 10000.0)
-				      * sectp->sct_oil);
-		max_oil = vl_find(V_OIL, mp->m_vtype, mp->m_vamt, mp->m_nv);
-		if (sp->shp_item[I_OIL] > max_oil)
-		    oil_gained = max_oil - sp->shp_item[I_OIL];
-		sp->shp_item[I_OIL] += oil_gained;
 		product = &pchr[P_OIL];
+		oil_gained = roundavg(total_work(100, etus,
+						 sp->shp_item[I_CIVIL],
+					         sp->shp_item[I_MILIT],
+						 sp->shp_item[I_UW])
+				      * (double)sp->shp_effic / 100.0
+				      * (double)sectp->sct_oil / 100.0
+				      * prod_eff(product, sp->shp_tech));
+		max_oil = vl_find(V_OIL, mp->m_vtype, mp->m_vamt, mp->m_nv);
+		if (sp->shp_item[I_OIL] + oil_gained > max_oil)
+		    oil_gained = max_oil - sp->shp_item[I_OIL];
+		sp->shp_item[I_OIL] += oil_gained;
 		if (product->p_nrdep != 0 && oil_gained > 0) {
 		    resource = ((s_char *)sectp) + product->p_nrndx;
 		    *resource -= roundavg(oil_gained *
@@ -182,8 +187,14 @@ upd_ship(register struct shpstr *sp, register int etus,
 		}
 	    }
 	    if ((mp->m_flags & M_FOOD) && sectp->sct_type == SCT_WATER) {
-		sp->shp_item[I_FOOD] += ((sp->shp_item[I_CIVIL] * etus) / 1000.0)
-		    * sectp->sct_fertil;
+		product = &pchr[P_FOOD];
+		sp->shp_item[I_FOOD] += roundavg(total_work(100, etus,
+							    sp->shp_item[I_CIVIL],
+							    sp->shp_item[I_MILIT],
+							    sp->shp_item[I_UW])
+						 * (double)sp->shp_effic / 100.0
+						 * (double)sectp->sct_fertil / 100.0
+						 * prod_eff(product, sp->shp_tech));
 	    }
 	    if ((n = feed_ship(sp, etus, &needed, 1)) > 0) {
 		wu(0, sp->shp_own, "%d starved on %s\n", n, prship(sp));